If a product bears the 100% Stamp, then all its grain ingredients are whole grains. There is a minimum requirement of 16g (16 grams) - a full serving - of whole grain per labeled serving, for products using the 100% Stamp. If a product bears the Basic Stamp, it contains at least 8g (8 grams) - a half serving - of whole grain, but may also contain some refined grain. Even if a product contains large amounts of whole grain (23g, 37g, 41g, etc.), it will use the Basic Stamp if it also contains extra bran, germ, or refined flour. Each Stamp also shows a number, telling you how many grams of whole grain ingredients are in a serving of the product.