Features: In-mould construction, inner thickened EPS foam and the outer hard shells engineered to ensure fine shock absorption for your head protection and security. 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 riders stand out in the darkness and increase the security.  The light is waterproof and rainproof and can be fully charged in just 2 hours. Single-hand dial actuated retention system on the back of the cycling helmet provides easy adjustment and tightens the overall fit on your head. Soft padded chin strap protects your chin from discomfort. 21.65-24.41 Inches, take a head measurement to see if it fits. 12 vents on the biking 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 airflow over the head and bring cool comfort for the riders. High-performance interior padding, soft, comfortable and moisture-wicking. Removable and Hand Washable. Come with a portable bag, very convenient to carry the cycle helmet outside or store.