Featuresr integrated in mold pc shell with 81gl density eps impact foamr fit adjustment back wheel 20 24 inches for comfort wearingr 19 vents seek for ample and good ventilationr with a detachable visor to block sun light and add coolingr removable inner padding with bug screen to absorb shock and sweat and prevent bugr breathable and soft chin guard and head protective thick paddingr specially designed for mountain bike cycling skating roller skating etcr note please do not appl