Features:In-mold construction, inner thickened EPS foam and outer hard shells designed to provide fine shock absorption for the protection and safety of your head. The foam of this bike helmet is thicker than 17 mm (0.67 in), practical and sturdy, providing stronger protection.Built-in detachable USB light with 9 lighting modes, it can make cyclists stand out in the dark and increase safety.The light is waterproof and rainproof and can be fully charged in just 2 hours.The one-handed dial-operated retention system at the back of the bike helmet allows for easy adjustment and tightens the overall fit on your head. The soft padded chin strap protects your chin from discomfort. 21.65-24.41 inches, take a head measurement to see if it fits.The 12 vents on the cycling helmet are designed according to the wind tunnel principle. The shape and angle of each ventilation hole are the perfect crystallization of mechanics and aesthetics. They can perfectly move the airflow over the head and bring cool comfort to cyclists.High-performance inner padding, soft, comfortable and moisture-wicking. Removable and hand washable. Come with a portable bag, very convenient to carry the bike helmet outdoors or in the store.Features:Color: white, black, blue, pink (optional)Size:M: Item Size: 265 * 200 * 160mm / 10.4 * 7.9 * 6.3inchItem Weight: 340g / 12.0 ozPackage size: 268 * 210 * 160 mm / 10.6 * 8.3 * 6.3 inchesPackage Weight: 380g / 13.4 ozL: Item Size: 275 * 210 * 165mm / 10.8 * 8.3 * 6.5inchItem Weight: 380g / 13.4 ozPackage size: 276 * 225 * 168 mm / 10.9 * 8.9 * 6.6 inchesPackage Weight: 400g / 0.9lbPacking list:1 * Bicycle Helmet