The only amino acid and protein source designed specifically for male vitality and performance
Grassfed Whey Isolate
The only amino acid and protein source designed specifically for male vitality and performance
We are not the men our ancestors were.
This isn't meant negatively, it's a wake-up call. Our ancestors were not exposed to hormone disrupting chemicals and had access to more nutritionally dense foods that were grown and bred on fertile lands.
Despite the problem at hand and given all that modern science now has to offer, protein companies have chosen in favour of quantity and taste (containing soy, flavourings & additives) rather than scientific development; sacrificing men's overall health and hormonal profiles.
THE STATISTICS
20%
Generational decrease in men's testosterone levels since the 1980's.
50%
Estimated reduction sperm counts among Western men.
Soy Lecithin
Conflicting research around soy and men's testosterone. Soy lecithin is often sourced from GMO soybeans and is cheap.
Flavourings
Flavourings (even "natural") and other unnecessary additives disrupt metabolism, increase calorie intake and spike your glucose.
This isn't meant negatively, it's a wake-up call. Our ancestors were not exposed to hormone-disrupting chemicals and had access to more nutritionally dense foods that were grown and bred on fertile lands.
Despite the problem at hand and given all that modern science now has to offer, protein companies have chosen in favour of quantity and taste (containing soy, flavourings & additives) rather than scientific development; sacrificing men's overall health and hormonal profiles.
THE STATISTICS
20%
Generational decrease in men's testosterone levels since the 1980's.
50%
Estimated reduction sperm counts among Western men.
Soy Lecithin
Conflicting research around soy and men's testosterone. Soy lecithin is often sourced from GMO soybeans and is cheap.
Flavourings
Flavourings (even "natural") and other unnecessary additives disrupt metabolism, increase calorie intake and spike your glucose.
So we decided to design the first protein that is completely aligned with men's health.
With a strategic cooperation between local farmers and specialists in the field of endocrinology, we set out to produce an exceptionally clean protein that is grounded in science and aligned exactly with men’s health, not against it. So we ask the question; what is your advantage?
We offer a risk-free money-back guarantee with one-time purchase orders.
Men's Performance. Elevated.
TESTOSTERONE LEVELS & SEXUAL HEALTH
Containing amino acids that support healthy testosterone levels and male sexual health.
REDUCES STRESS & CAUSES ZERO BLOATING
An exceptionally clean protein that mixes in seconds and causes no bloating.
OPTIMAL MUSCULAR HYPERTROPHY
The 'complete' protein source that provides fuel for rapid muscular growth and accelerated recovery.
IMPROVES METABOLISM & WEIGHT MANAGEMENT
Reach your diet goals faster with essential and non-essential amino acids.
So we decided to design the first protein that is completely aligned with men's health.
With a strategic cooperation between local farmers and specialists in the field of endocrinology, we set out to produce an exceptionally clean protein that is grounded in science and aligned exactly with men’s health, not against it. So we ask the question; what is your advantage?
We offer a risk-free money-back guarantee with one-time purchase orders.
Men's Performance. Elevated.
We offer a risk-free money-back guarantee with one-time purchase orders.
WHAT'S INSIDE
More Than Muscle - The Only 'Complete' Protein Source for Male Health & Vitality
As a protein made specifically for male health from accredited Irish pasture-raised dairy, GWI provides the 'complete' selection of essential and semi/non-essential amino acids in a nearly 100% native undenatured form - offering far more towards your health than just muscle. Click on the dropdowns to find out more!
*Per 30g Serving
Nutrional Information
*372KCal per 100g, 111.6KCal per Serving.
Muscular Hypertrophy & Protein Synthesis
Leucine: Leucine contributes to the process of muscular hypertrophy, which involves an increase in the size of individual muscle fibres. By activating the mTOR signalling pathway, leucine helps promote the growth and development of muscle tissue. Leucine is a key stimulator of muscle protein synthesis, the process by which the body builds new proteins, including muscle tissue. This is particularly important for individuals engaged in resistance training or seeking to build and maintain muscle mass.
Isoleucine: Isoleucine is involved in the stimulation of muscle protein synthesis. It works synergistically with leucine to support the growth and repair of muscle tissue, making it essential for individuals engaged in resistance training or seeking to maintain muscle mass.
Threonine: Threonine is a key component in the synthesis of proteins. It is incorporated into the structure of proteins during the process of translation, contributing to the formation of various tissues, enzymes, and structural proteins in the body. This is essential for overall growth, repair, and maintenance of tissues, including muscles.
Serine: Serine is involved in the synthesis of proteins, contributing to the structure and function of various proteins in the body. This is essential for the growth, repair, and maintenance of tissues, including muscles and organs.
Glutamic Acid: Glutamic acid is a non-essential amino acid that contributes to the synthesis of proteins. While the body can produce glutamic acid, it is an important component of many proteins, and its availability is crucial for the growth, repair, and maintenance of tissues.
Valine: Valine is involved in the process of muscle protein synthesis, contributing to the growth and repair of muscle tissue. This is particularly important for individuals engaged in resistance training or those looking to build and maintain muscle mass.
Phenylalanine: Phenylalanine is a building block for proteins, contributing to the synthesis of various proteins in the body. Proteins are essential for the structure, function, and regulation of tissues, enzymes, and other biological molecules.
Methionine: Methionine is a fundamental building block for protein synthesis. It is crucial for the formation of proteins, which play essential roles in the structure, function, and regulation of various tissues, enzymes, and other biological molecules.
Lysine: Lysine is a crucial component in the synthesis of proteins. It is involved in the formation of peptide bonds, contributing to the structure and function of various proteins in the body. Adequate lysine is essential for overall growth, repair, and maintenance of tissues, including muscles.
Hormone & Sexual Health
Arginine: Arginine is important for spermatogenesis, the process of sperm production. It plays a role in maintaining the health and function of the male reproductive system. Some studies suggest that arginine supplementation may have a positive impact on sperm quality.
Aspartic Acid: Aspartic acid has been suggested to play a role in the production of testosterone, a key male sex hormone. Some studies have explored its potential to stimulate the release of luteinizing hormone (LH), which in turn can signal the testes to produce more testosterone. However, the evidence is not consistent across all studies.
Tyrosine: Tyrosine is a key component in the synthesis of thyroid hormones, such as thyroxine (T4) and triiodothyronine (T3). These hormones are essential for regulating metabolism and overall energy balance in the body. Some studies suggest that tyrosine may play a role in the release of growth hormone. Growth hormone is important for growth, development, and the maintenance of various tissues, including muscle tissue.
Arginine: Arginine is a precursor to several hormones, including growth hormone, insulin, and glucagon. It plays a role in the regulation of these hormones, which are involved in growth, metabolism, and energy balance.
Stress Support
Tyrosine: Tyrosine has been studied for its potential to enhance cognitive function and mental performance, especially during periods of stress or fatigue. It is involved in the production of neurotransmitters that play a role in alertness, focus, and memory.
Tryptophan: Tryptophan is a precursor to serotonin, a neurotransmitter that plays a crucial role in mood regulation. Adequate tryptophan levels can contribute to the synthesis of serotonin, which is associated with feelings of well-being and can have a positive impact on mood.
Phenylalanine: Phenylalanine is a precursor to the neurotransmitter tyrosine, which, in turn, contributes to the synthesis of dopamine. Dopamine is involved in reward and pleasure pathways in the brain. Maintaining proper levels of phenylalanine supports the balance of neurotransmitters and may influence mood and overall mental well-being.
Sleep Support
Glycine: Glycine functions as an inhibitory neurotransmitter in the central nervous system. It can have calming effects on the brain and may act as a neurotransmitter involved in the regulation of mood and sleep. Some research suggests that glycine supplementation may have a positive impact on sleep quality.
Tryptophan: Tryptophan is also a precursor to melatonin, a hormone that regulates the sleep-wake cycle. Melatonin helps promote relaxation and contributes to the maintenance of a healthy sleep pattern. Adequate tryptophan intake may support the body's natural production of melatonin.
Immunity Support
Isoleucine: Isoleucine plays a role in supporting the immune system. Isoleucine is involved in the production of antibodies and helps maintain the overall health and function of the immune system.
Aspartic Acid: Aspartic acid, like other amino acids, is involved in supporting the immune system. It plays a role in the synthesis of immunoglobulins, which are antibodies that help the body defend against infections and foreign substances.
Serine: Serine plays a role in the production of antibodies and immunoglobulins, which are critical components of the immune system. Adequate serine is necessary for the proper functioning of the immune response against infections and foreign substances.
Glutamic Acid: Glutamic acid is involved in the synthesis of glutathione, a powerful antioxidant that plays a key role in supporting the immune system. Glutathione helps protect cells from oxidative stress and supports the proper functioning of immune cells.
Alanine: Alanine is a component of antibodies, which play a key role in the immune system's defense against infections and foreign substances. Adequate alanine levels are important for the synthesis of these immune system proteins.
Valine: Valine is involved in the synthesis of antibodies, which are critical components of the immune system. Antibodies help defend the body against infections and foreign substances, contributing to overall immune system function.
Cysteine: Cysteine is a crucial component in the synthesis of glutathione, one of the body's most potent antioxidants. Glutathione helps neutralize free radicals and plays a key role in protecting cells from oxidative stress. This antioxidant activity contributes to overall health and may have implications for reducing the risk of chronic diseases.
Energy & Brain Health
Aspartic Acid: Aspartic acid is involved in the citric acid cycle (also known as the Krebs cycle), which is a critical part of cellular respiration. This cycle contributes to the production of adenosine triphosphate (ATP), the primary energy currency of cells. As a result, aspartic acid plays a role in energy production and metabolism.
Alanine: Alanine can be converted into pyruvate, a compound that plays a crucial role in energy production. In the context of muscle metabolism, alanine can serve as a source of energy during exercise by being converted into pyruvate and entering the energy-producing pathways.
Glutamic Acid: Glutamic acid is a precursor to alpha-ketoglutarate, an intermediate in the citric acid cycle (Krebs cycle). The citric acid cycle is a crucial part of cellular respiration, contributing to the production of adenosine triphosphate (ATP), the primary energy currency of cells.
Histidine: Histidine is involved in the synthesis of various neurotransmitters in the brain, including histamine and carnosine. Carnosine is believed to have neuroprotective properties and may contribute to cognitive function and brain health.
Lysine: Lysine is involved in the synthesis of carnitine, a compound essential for the transport of fatty acids into the mitochondria, where they are used for energy production. Adequate lysine levels support efficient energy metabolism.
Valine: Valine, along with other BCAAs, can potentially influence neurotransmitter synthesis in the brain. While the research in this area is ongoing, some studies suggest that BCAAs, including valine, may have a role in supporting cognitive function and mental performance. Valine can be converted into glucose in the liver through a process called gluconeogenesis. During prolonged exercise or periods of fasting, valine can provide an additional energy source by being converted into glucose, supporting overall energy production.
Metabolism & Weight Management
Leucine: Leucine has been associated with improved insulin sensitivity, potentially helping to regulate blood sugar levels. This can be beneficial for overall metabolic health and may play a role in reducing the risk of insulin resistance. Some research suggests that leucine may contribute to satiety and the regulation of appetite. This can be relevant for individuals looking to manage body weight and composition, as a feeling of fullness may help with dietary control.
Isoleucine: Isoleucine, along with other BCAAs, has been suggested to play a role in the regulation of blood sugar levels. It may contribute to improved insulin sensitivity and glucose uptake by cells, potentially benefiting individuals concerned with metabolic health.
Threonine: Threonine is involved in the metabolism of fats by contributing to the synthesis of phospholipids. Phospholipids are essential components of cell membranes and are crucial for the transport and utilisation of fats in the body.
WHAT'S INSIDE
More Than Muscle - The Only 'Complete' Protein Source for Male Health & Vitality
As a protein made specifically for male health from accredited Irish pasture-raised dairy, GWI provides the 'complete' selection of essential and semi/non-essential amino acids in a nearly 100% native undenatured form - offering far more towards your health than just muscle. Click on the dropdowns to find out more!
*Per 30g Serving
Nutrional Information
*372KCal per 100g, 111.6KCal per Serving.
Muscular Hypertrophy & Protein Synthesis
Leucine: Leucine contributes to the process of muscular hypertrophy, which involves an increase in the size of individual muscle fibres. By activating the mTOR signalling pathway, leucine helps promote the growth and development of muscle tissue. Leucine is a key stimulator of muscle protein synthesis, the process by which the body builds new proteins, including muscle tissue. This is particularly important for individuals engaged in resistance training or seeking to build and maintain muscle mass.
Isoleucine: Isoleucine is involved in the stimulation of muscle protein synthesis. It works synergistically with leucine to support the growth and repair of muscle tissue, making it essential for individuals engaged in resistance training or seeking to maintain muscle mass.
Threonine: Threonine is a key component in the synthesis of proteins. It is incorporated into the structure of proteins during the process of translation, contributing to the formation of various tissues, enzymes, and structural proteins in the body. This is essential for overall growth, repair, and maintenance of tissues, including muscles.
Serine: Serine is involved in the synthesis of proteins, contributing to the structure and function of various proteins in the body. This is essential for the growth, repair, and maintenance of tissues, including muscles and organs.
Glutamic Acid: Glutamic acid is a non-essential amino acid that contributes to the synthesis of proteins. While the body can produce glutamic acid, it is an important component of many proteins, and its availability is crucial for the growth, repair, and maintenance of tissues.
Valine: Valine is involved in the process of muscle protein synthesis, contributing to the growth and repair of muscle tissue. This is particularly important for individuals engaged in resistance training or those looking to build and maintain muscle mass.
Phenylalanine: Phenylalanine is a building block for proteins, contributing to the synthesis of various proteins in the body. Proteins are essential for the structure, function, and regulation of tissues, enzymes, and other biological molecules.
Methionine: Methionine is a fundamental building block for protein synthesis. It is crucial for the formation of proteins, which play essential roles in the structure, function, and regulation of various tissues, enzymes, and other biological molecules.
Lysine: Lysine is a crucial component in the synthesis of proteins. It is involved in the formation of peptide bonds, contributing to the structure and function of various proteins in the body. Adequate lysine is essential for overall growth, repair, and maintenance of tissues, including muscles.
Hormone & Sexual Health
Arginine: Arginine is important for spermatogenesis, the process of sperm production. It plays a role in maintaining the health and function of the male reproductive system. Some studies suggest that arginine supplementation may have a positive impact on sperm quality.
Aspartic Acid: Aspartic acid has been suggested to play a role in the production of testosterone, a key male sex hormone. Some studies have explored its potential to stimulate the release of luteinizing hormone (LH), which in turn can signal the testes to produce more testosterone. However, the evidence is not consistent across all studies.
Tyrosine: Tyrosine is a key component in the synthesis of thyroid hormones, such as thyroxine (T4) and triiodothyronine (T3). These hormones are essential for regulating metabolism and overall energy balance in the body. Some studies suggest that tyrosine may play a role in the release of growth hormone. Growth hormone is important for growth, development, and the maintenance of various tissues, including muscle tissue.
Arginine: Arginine is a precursor to several hormones, including growth hormone, insulin, and glucagon. It plays a role in the regulation of these hormones, which are involved in growth, metabolism, and energy balance.
Stress Support
Tyrosine: Tyrosine has been studied for its potential to enhance cognitive function and mental performance, especially during periods of stress or fatigue. It is involved in the production of neurotransmitters that play a role in alertness, focus, and memory.
Tryptophan: Tryptophan is a precursor to serotonin, a neurotransmitter that plays a crucial role in mood regulation. Adequate tryptophan levels can contribute to the synthesis of serotonin, which is associated with feelings of well-being and can have a positive impact on mood.
Phenylalanine: Phenylalanine is a precursor to the neurotransmitter tyrosine, which, in turn, contributes to the synthesis of dopamine. Dopamine is involved in reward and pleasure pathways in the brain. Maintaining proper levels of phenylalanine supports the balance of neurotransmitters and may influence mood and overall mental well-being.
Sleep Support
Glycine: Glycine functions as an inhibitory neurotransmitter in the central nervous system. It can have calming effects on the brain and may act as a neurotransmitter involved in the regulation of mood and sleep. Some research suggests that glycine supplementation may have a positive impact on sleep quality.
Tryptophan: Tryptophan is also a precursor to melatonin, a hormone that regulates the sleep-wake cycle. Melatonin helps promote relaxation and contributes to the maintenance of a healthy sleep pattern. Adequate tryptophan intake may support the body's natural production of melatonin.
Immunity Support
Isoleucine: Isoleucine, play a role in supporting the immune system. Isoleucine is involved in the production of antibodies and helps maintain the overall health and function of the immune system.
Aspartic Acid: Aspartic acid, like other amino acids, is involved in supporting the immune system. It plays a role in the synthesis of immunoglobulins, which are antibodies that help the body defend against infections and foreign substances.
Serine: Serine plays a role in the production of antibodies and immunoglobulins, which are critical components of the immune system. Adequate serine is necessary for the proper functioning of the immune response against infections and foreign substances.
Glutamic Acid: Glutamic acid is involved in the synthesis of glutathione, a powerful antioxidant that plays a key role in supporting the immune system. Glutathione helps protect cells from oxidative stress and supports the proper functioning of immune cells.
Alanine: Alanine is a component of antibodies, which play a key role in the immune system's defense against infections and foreign substances. Adequate alanine levels are important for the synthesis of these immune system proteins.
Valine: Valine is involved in the synthesis of antibodies, which are critical components of the immune system. Antibodies help defend the body against infections and foreign substances, contributing to overall immune system function.
Cysteine: Cysteine is a crucial component in the synthesis of glutathione, one of the body's most potent antioxidants. Glutathione helps neutralize free radicals and plays a key role in protecting cells from oxidative stress. This antioxidant activity contributes to overall health and may have implications for reducing the risk of chronic diseases.
Energy & Brain Health
Aspartic Acid: Aspartic acid is involved in the citric acid cycle (also known as the Krebs cycle), which is a critical part of cellular respiration. This cycle contributes to the production of adenosine triphosphate (ATP), the primary energy currency of cells. As a result, aspartic acid plays a role in energy production and metabolism.
Alanine: Alanine can be converted into pyruvate, a compound that plays a crucial role in energy production. In the context of muscle metabolism, alanine can serve as a source of energy during exercise by being converted into pyruvate and entering the energy-producing pathways.
Glutamic Acid: Glutamic acid is a precursor to alpha-ketoglutarate, an intermediate in the citric acid cycle (Krebs cycle). The citric acid cycle is a crucial part of cellular respiration, contributing to the production of adenosine triphosphate (ATP), the primary energy currency of cells.
Histidine: Histidine is involved in the synthesis of various neurotransmitters in the brain, including histamine and carnosine. Carnosine is believed to have neuroprotective properties and may contribute to cognitive function and brain health.
Lysine: Lysine is involved in the synthesis of carnitine, a compound essential for the transport of fatty acids into the mitochondria, where they are used for energy production. Adequate lysine levels support efficient energy metabolism.
Valine: Valine, along with other BCAAs, can potentially influence neurotransmitter synthesis in the brain. While the research in this area is ongoing, some studies suggest that BCAAs, including valine, may have a role in supporting cognitive function and mental performance. Valine can be converted into glucose in the liver through a process called gluconeogenesis. During prolonged exercise or periods of fasting, valine can provide an additional energy source by being converted into glucose, supporting overall energy production.
Metabolism & Weight Management
Leucine: Leucine has been associated with improved insulin sensitivity, potentially helping to regulate blood sugar levels. This can be beneficial for overall metabolic health and may play a role in reducing the risk of insulin resistance. Some research suggests that leucine may contribute to satiety and the regulation of appetite. This can be relevant for individuals looking to manage body weight and composition, as a feeling of fullness may help with dietary control.
Isoleucine: Isoleucine, along with other BCAAs, has been suggested to play a role in the regulation of blood sugar levels. It may contribute to improved insulin sensitivity and glucose uptake by cells, potentially benefiting individuals concerned with metabolic health.
Threonine: Threonine is involved in the metabolism of fats by contributing to the synthesis of phospholipids. Phospholipids are essential components of cell membranes and are crucial for the transport and utilisation of fats in the body.
EXPLORE OUR OFFERS
Grassfed Whey Isolate
Made from Truly Grass Fed pasture-raised dairy and advanced cold crossflow microfiltration techniques, our protein maintains nearly 100% of its native undenatured form. Leaving an exceptionally clean whey isolate that is more bioavailable & higher in amino acids that support men's health. No shaker, no lumps & no bloating!
1 Pouch* (500g)
£34.99 / Pouch
MOST POPULAR
3 Pouches* (1.5kg)
£34.99 £29.99 / Pouch
BEST VALUE
5 Pouches* (2.5kg)
£34.99 £26.99 / Pouch
*Subscription Plans Available.
PURE. HIGHLY BIO-AVAILABLE. MADE WITH CARE.
NON-GMO
HORMONE FREE
MADE IN UK
GLUTEN FREE
OFFERS & BUNDLES
Grassfed Whey Isolate
Made from Truly Grass Fed pasture-raised dairy and advanced cold crossflow microfiltration techniques, our protein maintains nearly 100% of its native undenatured form. Leaving an exceptionally clean whey isolate that is more bioavailable & higher in amino acids that support men's health. No shaker, no lumps & no bloating!
*Subscription Plans Available
1 Pouch* (500g)
£34.99 / Pouch
MOST POPULAR
3 Pouches* (1.5kg)
£34.99 £29.99 / Pouch
BEST VALUE
5 Pouches* (2.5kg)
£34.99 £26.99 / Pouch
Mixes Instantly, No Lumps & Zero Bloating - No Protein Shaker Required.
Our whey protein isolate is intentionally unflavoured to keep it as clean and additive-free as possible. With incredible instantiation properties, it readily mixes in water, milk and other common liquids without lumps or the need for a shaker! GWI also has a Protein Digestibility Corrected Amino Acid Score (PDCAAS) of 1.0/1.0, the highest score achievable. Watch our short clip above to see how easy it is - no shaker required!
Exceptionally clean protein, simply packaged. GWI goes further!
Complexity is what holds people back the most from their health goals. To achieve the same protein and amino acid content as you do from Grassfed Whey Isolate, you'd need to spend ~£20 more per month whilst consuming significantly more sugars, calories, fat, lactose & other additives! Also our subscription plan puts your order on your doorstep every month without hassle and you save 10%! We keep it simple because simple is effective.
We offer a risk-free money-back guarantee with one-time purchase orders.
It's not in our DNA to cut corners.
ANIMAL WELFARE & ENVIRONMENTAL IMPACT
Our protein is sourced from Truly Grass Fed Irish dairy cows ensuring the highest level of animal welfare & lowest level of environmental impact.
UK MADE, GMP APPROVED
GWI is manufactured to the highest certification in GMP approved facilities with our ingredients subject to strict testing processes - certificates of analysis can be produced on request!
SUSTAINABLE PACKAGING
Our external shipping packaging is sourced from environmentally friendly FSC® approved partners.
Mixes Instantly, No Lumps & Zero Bloating - No Protein Shaker Required.
Our whey protein isolate is intentionally unflavoured to keep it as clean and additive-free as possible. With incredible instantiation properties, it readily mixes in water, milk and other common liquids without lumps or the need for a shaker! GWI also has a Protein Digestibility Corrected Amino Acid Score (PDCAAS) of 1.0/1.0, the highest score achievable. Watch our short clip above to see how easy it is - no shaker required!
We offer a risk-free money-back guarantee with one-time purchase orders.
Exceptionally clean protein, simply packaged. GWI goes further!
Complexity is what holds people back the most from their health goals. To achieve the same protein and amino acid content as you do from Grassfed Whey Isolate, you'd need to spend ~£20 more per month whilst consuming significantly more sugars, calories, fat, lactose & other additives! Also our subscription plan puts your order on your doorstep every month without hassle and you save 10%! We keep it simple because simple is effective.
We offer a risk-free money-back guarantee with one-time purchase orders.
It's not in our DNA to cut corners.
We offer a risk-free money-back guarantee with one-time purchase orders.
DON'T JUST TAKE OUR WORD FOR IT
Rated Excellent on Trustpilot
"Used Atavist's Atlas for a bit of time now... this new protein is exactly what I've needed. Low sugar, no soy, high protein."
- S, B
"Saw this advertised on Facebook and thought I'd give it a go... clean taste with no bloating... Great product thanks."
- D, M
"Now onto my second bag this is by far the cleanest protein I've tried. Can't go back to sweetened. Highly recommend."
- S,O
Rated Excellent on Trustpilot
"Used Atavist's Atlas for a bit of time now... this new protein is exactly what I've needed. Low sugar, no soy, high protein."
- S, B
"Saw this advertised on Facebook and thought I'd give it a go... clean taste with no bloating... Great product thanks."
- D, M
"Now onto my second bag this is by far the cleanest protein I've tried. Can't go back to sweetened. Highly recommend."
- S,O
We offer a risk-free money-back guarantee with one-time purchase orders.