Whey protein isolates are 90% pure protein by weight. They are the purest and most expensive form of whey protein that exists. That's why they are the first ingredients you read on the ON Gold Standard Double Rich Chocolate 100% Whey Dietary Supplement Powder label. By using whey protein isolates as its primary protein source, ON Gold Standard Double Rich Chocolate 100% Whey Dietary Supplement Powder is able to pack 24 grams of the purest muscle-building protein per serving, and a lot less of the fat, cholesterol, lactose and other stuff that you can do without. There's no question this is the standard by which other whey proteins are measured.