Ultralight Adult Men's Off Road Mountain Bike Bicycle Cycling Helmet EPS + PC Material MTB Helmet 21 Air Vents Body: use ONE STEP technology, EPS impact-resistant composite material. Super light material; Wind tunnel, duct design, effectively reduce wind resistance. Internal structure: high-quality foam layer, with regulating torsional, can adjust the size of head circumference. Painted color: as shown in figure Size: All in one size L. Suitable for head circumference under 65 cm and wide under 16 cm.