The RBS is an advanced dual aperture durable and low-profile auxiliary rear sight. It can be used with any front sight and was designed for more accurate aiming and faster target acquisition. Windage is easily and quickly adjusted without tools. RBS is readily mounted on any 1913 Picatinny rail making it ideal for use on M4 / AR-15 / M-16 platforms and on the FAB Defense K.P.O.S.