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, that provides maximum visibility both day and night.Features :"Optics Ready Stealth Series Night Sight Set with 0.240" Serrated Front and 0.238" Serrated Square Rear"Yellow Front Ring with Domed Lens and Green Tritium and Blank Rear with Domed LensesDesigned for Sig Sauer Optics Ready Pistols with P-Series Dovetails