Certified multi low force impact helmet (ATSM 1492) and Certified single high impact helmet (CPSC 1203) Specially formulated EPS foam to protect against multiple impacts and 5 times more protective than soft foam helmets Lightweight construction with soft, sweat absorbing sizing liners and additional padding supplied for a comfortable and secure fit Did you know, that the actual helmet shell size of S1 Lifer Helmets stays the same? It is the sizing liner supplied with the helmet that makes it fit that size range. S1 Helmet Co are an independently owned and operated brand that is deeply rooted in the Californian skateboarding, longboarding, BMX and roller derby scenes. Today S1 Helmet Co has an extensive line of protective helmets that are rapidly becoming known throughout the industry, thanks to their unrelenting approach to style and safety.