"CAIRBULL profession helmet adopts durable tough shell with soft liner which could absorb external pressure caused by crash in outdoor activities.   Features: The skateboard helmet adopts durable tough shell with soft liner which could absorb external pressure caused by crash in cycling activities. With removable, protective, sweat absorption lining pad, comfortable to wear and easy to wash. 18 vents design effectively reduce air resistance and sweating. Rotary internal regulator adjusts the tightness of helmet. The helmets come with an adjustable strap which make it flexible to fit the size.   Specification: Material: EPS + PC Vent qty: 18 vents Details: Package Size: 31 * 21* 18cm / 12.2 * 8.2 * 7.0in   Package List: 1 * Bike Helmet   Note: Please allow a little size difference (1-3cm) due to different manual measurement. Thanks!"