Specifications: Material: Polycarbonate shell, EPS buffer layer, polyester fiber strap Technology: One-piece molded helmet Size: M: 54-58 cm( 21.26-22.83 inches) L: 56-62 cm (22.04-24.40 inches) Internal dimensions: 18 x 22 cm (7.08 x 8.66 inches) External dimensions: 33.5 x 20 x 21.5 cm (13.18 x 7.87 x 8.46 inches) Weight: 375 g (0.82 lbs) Ventilation holes: 13 Certifications: CPSC 1203 + EN1078 + CE Core Features: Safety First: Certified by CPSC 1203 + EN1078 + CE, featuring a polycarbonate shell and shock-absorbing EPS foam for reliable impact protection. Suitable for mountain biking, road cycling, and commuting, balancing durability and comfort. Lightweight & Durable: Full-wrap design with an impact-resistant polycarbonate shell and energy-absorbing EPS foam layer, delivering high-strength protection while remaining lightweight for a freer and more comfortable ride. Enhanced Airflow: Stylish design with multiple color options. 13 tunnel ventilation holes and internal airflow channels work together to dissipate heat, making it ideal for long-distance rides. Accessories: Includes a removable and washable inner liner. The extended visor effectively blocks sunlight, flying insects, and branches during rides. Customizable Fit: Rear dial adjustment system allows for a personalized head circumference fit, suitable for most teens and adults (unisex).