The size of football helmets vary depending on the brand. Just because you worn a "large" in brand X doesn't indicate a "large" in brand Y will be the same size. This is why it is critical to first size yourself before selecting one that fits adequately. Size matters when it comes to protection. The larger the better. That's why many colleges and professional teams require players to wear helmets certified by their institution as being large enough for their protection needs. There are three main types of football helmets: full-shell, half-shell, and composite. Full-shell helmets are made from plastic or steel and have a complete outer shell that covers the head and face. They are most commonly used by quarterbacks (ironically, this type of helmet was originally designed for baseball players). Quarterbacks need full-shell helmets because they need maximum coverage for maximum protection. If they were allowed to use smaller helmets, they would be at risk of suffering a serious brain injury if they were hit in the head with an object. Half-shell helmets only cover the top half of the head and face. They are recommended for defensive backs and linebackers who don't want to restrict their view of the field. Half-shell helmets are also popular with kids who play soccer since they allow them to wear a helmet while still looking good playing their favorite sport.