The Night Fision Perfect Dot Tritium night sight provides maximum visibility both day and night. Their patent-pending injection molded sleeve design not only holds the tritium vial securely in place, it creates a brighter and more durable ring. For Glock 17, 17L, 19, 22, 23, 24, 25, 26, 27, 28, 31, 32, 33, 34, 35, 37, 38, 39. Perfect Dot Night Sights with added daytime florescence One of the brightest Tritium Night Sights on the market CNC Machined out of high quality 4140 steel Black Nitride coating used to improve wear and corrosion resistance Installation: Contact Professional Gunsmith Built in the USA with Swiss Tritium