The ncstar ar-15 detachable rear a2 iron back-up sight (dual aperture) is precision-made with aluminum and steel.The fixed a2 design is adjustable for windage and elevation and it mounts onto weaver and picatinny-type rails.This 2.7"-long sight weighs just 5.1 oz.Type: RearFrame Material: AluminumFrame Color: BlackFirearm Fit: AR-15Base Configuration: Picatinny RailStyle: PicatinnyFront Material: N/ARear Material: SteelFront Color: N/AFirearm Type: AR Rifle