The NcSTAR 1x42 R/G Dot Reflex Sight has integrated iron sight. It features electronic on/off switch and integrated weaver side rail. Allowing a lot of rail space for a Magnifier or backup iron sights on the firearm. The Combat Reflex Sight is set at the proper AR-15 height to co-witness the Dot Reticle with your Iron Sights. The Optic height will allow a more comfortable and natural cheek rest on your AR-15 stock. There is a Picatinny style rail mounted to the left side of the optic for attaching accessories like a laser or flashlight. The rail is also removable. Uses a CR123A battery for a long battery life. Integrated Weaver & Picatinny type mount. Fits virtually any Weaver/Picatinny rail, making it possible to fit onto a wide variety of firearms. Unlimited Eye Relief. LED (Light Emitting diode) 100% safe for the eyes.