Features: There is an adjustment knob on the back of the bike helmet to help adjust the heads circumference. The helmet is made of thickened multi-density EPS foam material, which can effectively absorb impact energy and minimize the risk of injury to the heads during impact. The bike helmet\'s removable goggles shade can be used as sunglasses to protect your face from sandstorms as well as strong uv rays. The riding helmet is made of lightweight materials and is lined with breathable material for comfort. Using a professional aerodynamic and ventilation design, the air passes through the bike helmet to help increase speed and keep you cool.