Bike helmets are indispensable in cycling as only on the premise of safety can we enjoy riding freely. This high-end bike helmets with 18 ventilation holes can disperse the air resistance and reduce the wind resistance. The inner lining is recommended to be washed once a month, so that we design the removable 3D protective lining. There is a buckle can be drug up and down to help wrap comfortable. 360?? head circumference adjustment allows most people to wear.