Specifications: Head Size Fit: M for 54-57cm(21.25-22.44in), L for 58-61cm(22.83-24.0in), XL for 60-62cm(23.62-24.4in) Material: PC Shell + EPS Inner Buffer + Strap Polyester Technology: Integrated Internal Size: 17*22cm(6.7*8.67in) Outside Size: 34*22*19cm(13.38*8.67*7.48in) Weight: M-350g(0.77lb), L-380g(0.84lb), XL-390g(0.86lb) Vents: 18 Certificate: CPSC 1203 + EN1078 Package: 1*Mountain Bike Helmet, 1*User Manual, 1*Sun Visor, 2*Screws SAFETY FIRST: Our best-performance mountain bike helmet complies with U.S. CPSC and E.U.CE Safety Standards for Bicycle Helmets, offering versatility and sufficient protection to start your splendid adventure SOLID CONSTRUCTION: Full Coverage Tough polycarbonate outer shell fused?helmet's?impact-absorbing EPS foam layer for durability without excess weight, riding with free and comfortable READ TO GO: Sleek design and diverse colors,?it's?combined with 18 wind tunnel vents and internal channeling for heat dissipation during long journey riding ACCESSORIES: With washable and removable padding inside, a big visor for sunlight proof and protects the head from small objects 3 SIZE AVAILABLE: The rear dial for customizing circumference with the easily adjustable system, with?3 sizes?available?it fits most youth, adults, men, and?women's?head sizes