Tank tops are required in amateur boxing as well as Olympic boxing. They are often a point of expression in the boxer's outfit. Some boxers may choose to wear a tank top that expresses their favorite color or colors of their nationality. Collegiate boxers, in particular, may coordinate their outfit to match their school colors. In some events, boxing organizations such as USAB, may require boxers to wear blue or red. The normal reasoning behind wearing a shirt is to reduce cuts to the body; however, in professional boxing boxers do not wear shirts. Instead, professional boxers use petroleum jelly to provide a slick surface for punches to slide on. This reduces friction from punches.