Imo safety signs contain symbols for immediate recognition of instructions, directions, and identification. In the Dark, Lumi-Glow plastic signs are visible with a green-yellow glowing surface. During light conditions, any light source can ?energize? the photo luminescent material with glow rating up to 10 hours. In regular light the Sign surface is nearly white with a slight green appearance. Durable, semi-rigid material is ideal for extended indoor and outdoor conditions. Resistant to UV light, some chemicals, and moisture.