Eotech 556 Buttons on left side of sight (not in back) to work specifically with NV or magnifiers CR123 Lithium batteries; model with 65 MOA ring/1 MOA dot reticle Compatible with Gen I-III+ Night Vision Systems (tandem operation) Raised 7mm base with knurled cross bolt Interfaces to 1" Picatinny (MIL-STD-1913) rail Operation Optics: Transmission holography - parallax free Magnification: 1x Eye Relief: Unlimited Length/Width/Height: 5.1"x2.1"x2.8" (130x53x71 mm) Weight: 11.9 oz (372 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) Adjustment Range: +/- 40 MOA travel Mount: 1" Picatinny (MIL-STD-1913) rail Return to Zero: Repeatable to 1 MOA after re-mounting Heads-Up-Display Window Optical Surfaces: Anti-glare coating Window Dimensions: 1.20" x 0.85" (30 x 23mm) Front Window Material: 1/8" solid glass Rear Window Material: Shatter resistant laminate (3/16" thick) Field of View (100 yds): 30 yds (28m) at a 4" eye relief Standard Reticle: A65/1 Electrical Brightness Adjustment Range: 146,000:1 brightest to lowest Night Vision Brightness Range: 1280:1 with NV switch engaged Function Button Location: Left side near the rear of sight Power Source: 2x 3.0V Lithium 123 batteries Battery Life: 1,100 continuous hours at nominal setting 12 Brightness Settings: 30 settings with scrolling feature (10 settings for NV use) Auto Battery Check Indicator: Flashing reticle upon start-up Auto Shut-down: At 8 hrs- programmable to 4 hrs