NMC 0.050 rigid plastic fire sign. The location of flammable substances, fire alarms, hoses, extinguishers, blankets, and evacuation exits and routes must be clearly marked throughout your facility to not only prevent a fire, but also help ensure your employees' safety. Indoor/outdoor use. Mounting: yes. Good chemical resistance. Maximum temperature: 183 degrees F. Measures 7-inches length by 7-inches height. Legend "FIRE DOOR PLEASE KEEP CLOSED".