IdentiFire™ Safety products feature material that is Made in AMERICA. They feature 3M Retro-Reflective and our photoluminescent (Glow in the dark) material that is molded together to withstand the harshest environments. These have been tested by firefighters, for firefighters. Any kind of light will charge these to full brightness (The sun, flashlights, headlights, etc) and they will continue to glow for up to 20 hours. These Letters/Numbers are 2″ tall and vary in width depending on which character you choose. They work great for helmets or general numbering/lettering.