Signs are made of pressure sensitive vinyl film, washable, non-toxic, non-radioactive and abrasive-resistant. In total "black-out" or "brown-out" signs will show the way out of emergency situations. Signs require only a minimal exposure to a natural or artificial light to glow over and over again. For use on most clean, smooth non-porous surfaces. Glows for several hours and recharges in less than a minute.