When it comes to tritium gun sights, aluminum sleeves and painted-on white rings are the norm. Night Fision breaks the mold, literally. Their patented, injection molded sleeve design not only holds the tritium vials securely in place, it creates a brighter and more durable ring, they call The Perfect Dot(TM), that provides maximum visibility both day and night. Features: Perfect Dot(TM) Night Sights with added daytime florescent or phosphorescent ring Brightest Tritium Night Sights on the market CNC Machined out of high quality steel Black Nitride coating used to improve wear and corrosion resistance Installation: Gunsmith Recommended Built in the USA with Swiss Tritium Fits Smith & Wesson M&PA(R), M&PA(R) M2.0(TM), SD9 VE(TM), SD40 VE(TM) Models (Excluding M&P SHIELD(TM), Compact, & C.O.R.E. Series & Optics Ready Slide)