Standardized by the DEA, ATF, and FBI SWAT, the Model 552 is by far the most popular HWS model. This NV compatible, AA battery model is the sight of choice by military units like Stryker Brigade, 10th Mountain, and 3rd Infantry. It is battle proven to withstand the abuse that any harsh environment, high powered weapon platform, or military mission can dish out. Compatible with Gen I-IV Night Vision Systems (Tandem Operation) AA Battery model (supports Lithium and Alkaline) 65MOA ring/1 MOA dot reticle includes rugged aluminum hood assembly and knobbed, tool-less mounting bolt interfaces to 1 inch Picatinny (MIL-STD-1913) or Weaver rail Operation Optics: Transmission holography - parallax free Magnification: 1x Eye Relief: Unlimited Length/Width/Height (inches): 5.4 x 2 x 2.25 (137x50.8x57 mm) Weight: 10.9oz (309 grams) Temperature: -40 to 150 F (using AA lithiums); -20 to 140 F (all other battery choices) Waterproof: Submersible to 33 ft depth Sealing: Fogproof internal optics Adjustment (per click): 0.5 MOA (1/2 inch at 100 yds) Adjustment Range: +/- 40 MOA travel Mount: 1 inch Picatinny (MIL-STD-1913) or Weaver rail Return to Zero: Repeatable to 1 MOA after re-mounting Heads-Up-Display Window Optical Surfaces: Anti-glare coating Window Dimensions (inches): 1.20 x 0.85 (30 x 23mm) Front Window Material: 1/8 inch solid glass Rear Window Material: Shatter resistant laminate (3/16 inch thick) Field of View (100 yds): 30 yds (28m) at a 4 inch eye relief Electrical Brightness Adjustment Range: 146,000:1 brightest to lowest Night Vision Brightness Range: 1280:1 with NV switch engaged Power Source: 2x 1.5V AA batteries (supports lithium, alkaline, or rechargeable) Battery Life: 1,000 continuous hours (lithium) at nominal setting 12; 600 continuous with AA alkaline 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