"With a in-mold construction, this bike helmet delivers optimal protection and _x000D_ Features 21 vents for maximum air flow, breathable mesh pad to keep the helmet breathable and odor free, and an adjustable dial for a secure and comfortable fit. It is built for performance and designed for comfort and safety during your ride._x000D_ _x000D_ Features:_x000D_ In-mold PC shell improves strength and reduces weight._x000D_ EPS foam liner for maximum impact protection and integrity._x000D_ 21 air vents provide good aerodynamics and keep you cool._x000D_ Adjustable rotary back dial provides secure, comfortable fit._x000D_ Inner mesh pad for great breathability and comfort._x000D_ Two sizes for you to choose: S/M (20.5"" - 22.8""); M/L (22.8"" - 24.4"")._x000D_ _x000D_ Specifications:_x000D_ Material: PC Shell & EPS Foam_x000D_ Vents: 21_x000D_ Color: Black / Green / White (optional)_x000D_ Size:_x000D_ S/M: 52 - 58cm / 20.5 - 22.8in_x000D_ M/L: 58-62cm / 22.8 - 24.4in_x000D_ Weight: S/M (195g); M/L (225g)_x000D_ _x000D_ Package List:_x000D_ 1 * Bike Helmet"