Safety helmet for motorcyclists or mountaineers is adaptable to different sizes of head by use of air-chambers inflated with air from user's mouth

摘要

The helmet has a hard outer shell, designed to protect the user's head against penetrating blows and mechanical shock. A chin strap holds the helmet in place. There is insulating material inside the helmet in addition to air chambers. The air chambers are inflated with air from the user's mouth.