Tough biscuits usually use less fat and sugar in the formula. The standard ratio is oil: sugar = 1: 2.5, oil + sugar: flour = 1: 2.5. The moisture content is no more than 7%. Representative products of tough biscuits include irregular-shaped products such as animal and toy biscuits. The tough product gets its name because it requires a long time to mix the flour to form a dough with extremely strong toughness.