FAB Defense FXRBS Rear BackUp Sight for AR15 M16 M4 Dual Aperture Low Folded Profile SpringLocked Deployment Black Polymer Met

The RBS is an advanced lowprofile durable auxiliary rear sight. It can be used with any front sight but has been designed to provide an extreme optical advantage. It is readily mounted on any 1913 Picatinny rail making it ideal for use on M4AR15M16 platforms. The sight can be used as a primary or backup sight and the ergonomic angelwingshaped front shroud helps center the image with any front sight. The low folded profile is smooth and inconspicuous and will not snag on gear webbing or brush. The dual apertures are 3mm for longer eye relief mounting low light and faster target acquisition and 1.5mm for shorter eye relief mounting and greater accuracy. The sight is also made of extremely durable highgrade polymer and metal and has an instant springlocked deployment mechanism that will not slip break or deform.