Leatt MTB AllMtn 1.0 Men Helmet Titanium S 51-55cmPolymer Compound shell in three sizes MaxiFlow impact foam air channels effective even at low speed 360 Turbine Technology Reduced peak brain acceleration by up to 30% at impact speeds associated with concussion Reduces peak brain rotational acceleration by up to 40% Extended rear coverage for added protection Adjustable visor with breakaway function for rotational impact force reduction In molded impact foam for great energy absorption Maximized