The S1 Lifer Helmet is one of the best fitting and safest helmets for Skateboarding, Longboarding, BMX, Scootering, Roller Skating and Roller Derby. The Lifer Helmet uses a specially formulated EPS Fusion Foam which allows it to protect your head from multiple low force impacts as well as high impacts. The Lifer Helmet is a certified "multi-impact" helmet and is up to 5x more protective than the soft foam non-certified helmets. The Lifer helmet is a break through design combining the added safety of a CPSC and ASTM certified helmet with the comfort and fit of a non-certified helmet. The S1 Lifer Helmet is the best fitting High impact and Multiple Impact helmet on the market. Please note that this helmet comes with a single sizing liner. Additional sizing liners are available for purchase.