The TRUGLO Fiber Optic AR-15 Front Gas Block Sight is what you need for your AR-15. This sight is designed to mount to an AR-15 Gas block. This sight features a green fiber optic that has a push button to illuminate the sight in total darkness. This sight includes a sight adjustment tool. Specifications and features: TRUGLO Fiber Optic AR-15 Front Gas Block Sight TG115 Extra long, super bright, protected green fiber Integral mount for Mil-Spec. 1913 Picatinny rails Designed to mount on front gas blocks Click elevation adjustment Includes sight adjustment tool Includes optional push-button light for use in complete darkness CNC-machined construction Green front Black Uses three SR60 batteries Fits: AR-15 and similar with lower gas block height