With its timeless design, killer color range and our unique glossy finish, the Brainsaver is a staple of our helmet collection. And with our stink-free, moisture-wicking Sweatsaver Liner inside, its a helmet you'll use for years to come. Sweatsaver replacement liner are also sold separately in various colors to customize your helmet. 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 – 20.50" S 20.60 – 21.30" M 21.40 – 22.00" L 22.10 in – 22.90" XL 23.00 – 24.00"