helmet, bicycle helmet, adult helmet

Helmet is a protective device for the head. It is a cap worn during training and combat, and an essential tool in transportation. It is usually semi-circular in shape and consists mainly of a shell, a lining, and a suspension system. The shell is made from special steel, fiberglass, reinforced plastic, leather, nylon, and other materials to protect the head from bullet fragments and other impacts. In ancient China, it was referred to as armor for the head, head armor, or skull protection.