Bern Macon Summer EPS Helmet, Carbon Certified ASTM F 2040, CPSC and EN 1078 Carbon Outer shell with EPS sets a new bar for quality combined with the lightest bomber head protection around Low profile Sink Fit doesn't look like a spaceship landed on your head Compatible to upgrade a winter liner (sold separately) for winter sports Fits Heads 59-60.5 cm in circumference.