Bern Unlimited Watts Hard Hat Summer Helmet, Small, Satin White 21 - 21 7/8 in HARD HATS are designed for slower speed impacts - MULTI-IMPACT design and DOES NOT meet the Single Impact rating for CPSC, ASTM or EN 1078 ratings Soft and comfortable BROCK foam is the only fully open cell construction that permits full breathability around your head Unique Construction very comfortable for a wide range of conditions; THIS IS NOT A HELMET Separate Winter liner can be purchased to convert to either cold weather bike riding, or for skiing/snowboarding