It is a simple cap that prevents foreign matter from entering into equipment or board that no longer requires penetrating holes and penetrations (cable or pipe). It can also be used as a protection for spare holes that are reserved for wiring cables. It is possible to easily fit the BN nozzle with a one-touch-push. (BN20S only) It is made of flame-retardant (UL94 V-2) nylon resin which possesses heat resistance and tracking resistance and contains no harmful substances.