Bern Unlimited Allston Helmet with Black Flip Visor 21 1/4 - 22 1/2 in Zip mold liquid foam technology offers a thinner profile than the standard EPS grey foam other brands use, giving you a much smaller helmet shape Flip Visor gives you on the fly capability to deflect elements or increase your hipster style - depending on what you are gunning for Crank Fit dial on back of helmet quickly secures or loosens the fit around your head, super easy to adjust - even on the fly Meets Safety Certification ASTM F 2040, CPSC and EN 1078 and WINTER UPGRADE KIT AVAILABLE SEPARATELY