A photoluminescent 4 inch by 4 inch square. For marking the exit door latch. An easy peel and stick application. Activated by natural artificial light, Safe-T-Nose Square Door Hardware Markings provide a steady glow to guide people in all lighting conditions. Glows for many hours after the lights go out. Unlimited recharging. The Brightest, Longest Lasting, Nontoxic, Nonradioactive Glow available. UV Light and Oxidation resistant. Smooth easy cleanable surface.