Glows in total darkness after only 30 seconds of exposure to artifical or natural light. Draws attention to light switches, equipment controls, fire extinguishers, etc. during a blackout. Will glow the brightest the first 30 minutes after activation and will remain clearly visible for up to eight hours in a totally dark room. Phosphorescent media is laminated between two polymer films and is backed by a pressure-sensitive adhesive. Not recommended for outdoor use.