The International Protection (IP) Marking code (sometimes called Ingress Protection) measures waterproof headlamps. You may notice the letters IP or IPX in the specifications. A headlamp with a rating of IPX4 can withstand rain, mist, and sweat. One labeled IPX7 or IPX8 can be submerged in water for 30 minutes and still operate. If there are no ratings, keep the headlamp dry.