According to Chinese national standard GB2894-2008 "Safety Signs", "Safety helmet must be worn" belongs to "command sign". The command symbol means that it must be observed.

There should be four permanent marks on the helmet: 1, manufacturer's name, trademark, model 2, production date, production certificate and verification, and production license number. Safety helmet is a shallow dome made of steel or similar raw materials to protect the top of the head, and it is a safety protection article to prevent the head from being injured by an impact object.