Shortest model sight yet! This sight is smaller than the former N-cell battery sight (511/551) and runs on a single 123 battery. It also has a longer battery life than the N-cell style sights. Smaller,lighter and always fast with three reticle options. With the new single battery configuration, the XPS allows more rail space than ever, leaving more room for rear iron sights or NV mount. Features & Benefits: Single transverse 123 battery to reduce sight length Shortened base only requires at most 2 3/4 inch of rail space compared to the 4 inch N battery sights Battery cap and latch are eliminated and replaced with a simple O-ring, tethered cap; better sealing is achieved Battery compartment is now separated from the base to allow it to hover over the delta ring of the rifle Average battery life at brightness level 12 is roughly 500-600 hours, 3X battery life of N cell sights Three reticle options: 0- 65MOA circle with 1 MOA aiming dot, 1-single 1MOA aiming dot, 2-65MOA circle with two 1MOA aiming dots Available in Night Vision (XPS3) and non- Night Vision (XPS2) versions. The numbers reflect the number of the buttons on the back of the sight Optics: Transmission holography - parallax free Magnification: 1x Eye Relief: Unlimited Length/Width/Height: 3.75"x2.4"x2.4" (95.25X60.96x60.96) Weight: 8.8 oz (250 grams) Temperature: -40 to 150 F Waterproof: Submersible to 33 ft depth Sealing: Fogproof internal optics Color/Finish: Non reflective black with hard coat finish Adjustment (per click): 0.5 MOA (1/2" at 100 yds),0.25 MOA (14" at 50 yds.) Adjustment Range: /- 40 MOA travel Mount: 1" Weaver or Picatinny (MIL-STD-1913) rail Return to Zero: Repeatable to 2 MOA after re-mounting Night Vision Compatibility: yes 10 setting (generation i-iii ) Warning: Requires State Department License for export