Trijicon's self luminous iron sights are proven to give shooters five times greater night fire accuracy-with the speed as instinctive shooting. That's why Trijicon Iron Sights are standard issue with hundreds of municipal and county law enforcement agencies, numerous state police departments and several federal agencies. The light is provided by glowing tritium gas-filled lamps which are fully warranted up to twelve years for the green dots found in the sights we sell. The green dots are the number one choice because they are the brightest dots available. In addition, Trijicon sights have a white outline around the glowing dots for the highest daylight visibility.