It is a component to cover mouth, to prevent invasion of expiration inside of shield and prevent fogging of shield. "AIR MASK" is made of rubber and to be fixed to head directly by strap. Therefore, it may be used for many models. For "AIR MASK 2", flat fastener is stuck to inside of helmet in mouth area by both sides sticky tape. Then, the component is adjusted by flat fastener so that it comes to close contact with face. "AIR MASK 3" is in the same type as "AIR MASK 2".