The QF B.U.S. (Back-Up Sight) can be used as both a back-up sighting system for rifle optics or as a primary sighting system. The sights must be manually flipped up and are secured using the sight's internal tensioning feature.AR15 Flip-Up Sights (Tactical) Front AR15 Flip-Up Front Sight - Back-Up Iron Sight Flip-Up A2 Front Sight Post folds down out of view of your optics when not in use The A2 Front Sight Post is fully adjustable for elevation Aluminum and Steel ConstructionAR15 Flip-Up Sights ( Tactical ) Rear AR15 Flip-Up Rear Sight - Back-Up Iron Sight Mounts onto the AR15 flat-top receiver, directly onto the Picatinny rail Aluminum and Steel ConstructionWeight (oz)3Width (in)1.1Length (in)1.3MaterialAircraft Grade Aluminum, High Strength SteelCoating TypeHard Coat Anodized FinishColorBlack