Trijicon DI Tritium/Fiber Optic Night Sights, Fits Glock 42/43/43X/48, Includes 2 Green Fiber Replacement Pieces and T10 Torque L-Key GL813-C-601106 Trijicon DI Night Sights feature a chemical and heat resistant fiber" finished with the same proprietary technique as the Trijicon ACOG" coupled with a tritium lamp capped with a sapphire jewel. This dual-illumination technology amplifies collected light" ensuring an ultra-bright aiming point in any light from daylight-bright to low-light to complete darkness. Designed for shooters who want daylight brightness and a constant aiming point" the dual illuminated Trijicon DI Night Sights are equipped with an industry-first" interchangeable fiber. This patent pending design not only allows the ability to replace the fiber in the field" it allows the user to choose among several fiber and ring retainer colors to configure a personalized aiming solution.