Pro® Glow has a non-radioactive chemical light source incorporated into a flexible vinyl film that glows in total darkness after exposure to artificial or natural light. The photoluminescent film light source is designed to absorb energy from any nearby ambient light such as fluorescent lamps or sunlight. Once the source of extraneous light is removed, Pro® Glow film immediately emits a light of its own. There is no limit to the number of times this product can be recharged. When fully charged, Pro® Glow provides positive luminance for up to 10 hours.