The Ncstar VDBRB Micro Red Blue Dot Reflex Optic Sight is compatible with AR15 Picatinny, MIL-STD 1913 rails, and Weaver. It features a 1.7" high Red and Blue Dot Reticule, and this reflex sight is compact and sleek in design. The 1.7" dot height is set for 1/3 Co-witnesses with AR15/M4 iron sights. No need for a 3/4" riser, this will attach directly to your AR-15 M16 or M4 rifle. Unlimited eye relief for flexible mounting with a built in auto locking quick release. Picatinny mount that is compatible with Weaver, Picatinny, MIL-STD 1913 rails. The Red and Blue Dot reticle is controlled by an electronic control panel with push button controls. The Electronic Control panel turns On/Off, adjusts the brightness levels, and changes the Dot Reticle from Red and Blue colors. Bikini style lens covers, mounting, and zeroing tools are included.