Our renowned Brainsaver rubber helmet is one of the best multi-impact helmets available. This helmet can be used as necessary protective gear for skateboarding, in-line skating ("rollerblading"), roller derby, and scooters. This helmet is not for bicycle use. As well, at Triple Eight we know that sweating while skateboarding sucks, so our techies here listened to our top riders, went back to the drawing board and developed the patented Sweatsaver liner that helps eliminate the smells, the stinging and the eye blurring that occurs from sweat. Our revolutionary liner has moisture-wicking layers that limit sweat drippage, an anti-bacterial treatment to make it virtually stink proof, and a 360-Degree wrap around design so that there is absolutely no liner separation. with our terry cloth construction, you can kiss that itchy head feeling goodbye. Our Sweatsaver liner is standard in all rubberized helmets and pro helmets, and is also sold individually in sizes XS – XL. Brainsaver Rubber Helmet Sizing Chart: To ensure a perfect fit, measure the circumference of your head starting in the middle of your forehead and match it with the sizes below. XS 20.10 in – 20.50 in (51-52cm) S 20.60 in – 21.30 in (52-54cm) M 21.40 in – 22.00 in (54-56cm) L 22.10 in – 22.90 in (56-58cm) XL 23.00 in – 24.00 in (58-60cm)