A football helmet is a protective evice used primarily in American football and Canadian football, the modern hard plastic version of which was created by Paul Brown. It consists of a hard plastic top with thick padding on the inside, a facemask made of one or more metal bars, and a chinstrap used to secure the helmet. Some players add polycarbonate visors to their helmets, which are used to protect eyes from glare and impacts. Helmets are a requirement at all levels of organized football, except for non-tackle variations such as flag football. Although they are protective, players can and do still suffer head injuries such as concussion. Each position has a different type of face mask to balance protection and visibility.