The Ncstar VDBRB Micro Red Blue dot reflex optic sight is compatible with AR15 Picatinny, MIL-STD 1913 rails and Weaver it features 1.7" height Red and Blue dot reticle and this reflex sight is compact and sleek designed. 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 rile. Unlimited eye relief for flexible mounting with built in auto locking quick release Picatinny mount that is compatible with Weaver, Picatinny, MIL-STD 1913 rails. 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 included.