This set of Hyper-Bright Tritium Night Sights from Meprolight is designed to improve handgun accuracy in bright light, low light, and no light. Two glowing green dots in the U-shaped rear sight help align the green front sight with your target, while the high-contrast yellow ring around the front lamp provides daytime aiming help. The green tritium lamps are self-powered, no batteries necessary, and warranted to keep working for 12 years. Please note that the manufacturer recommends professional installation for owners who aren't sure they have the knowledge or tools for the job.