Specifications: Head Size Fit: 56-59cm (22.04-23.22in) Material: PC Shell + EPS Buffer + Strap Polyester Technology: Integrated Internal Size: 17*22cm (6.7*8.67in) Outside Size: 36*22*18cm(14.17*8.66*7.08in) Weight: 390g (0.85lb) Vents: 16 Certificate: CPSC 1203 + CE EN1078 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 maximum 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 SIZE ADJUSTMENT: The rear dial for customized circumference with the easily adjustable system, fits for most youth, adults, men, and women's head sizes