All M550's have been upgraded to submersible 33 ft. water depth. Within this same feature upgrade, the membrane pad has been redesigned to greatly improve the tactile feel of the push button switches. The switches are designed with raised inlays to provide further separation between switch controls and reduce audible signature. Compatible with Gen. I-IV Night Vision Systems (tandem operation) Includes ruggedized hood assembly and knobbed, tooless mounting bolt Interfaces to standard 1" Weaver dovetail/Picatinny rail Factory pre-mounted with 2D Standard reticle pattern Aso available in a AA battery model with 2D standard reticle (supports Lithium and Alkaline) Specifications Optics: Transmission holography - 100% parrallax Magnification: 1x unlimited eye relief Length/Width/Height: 4 x 1.8 x 2.25 Weight (oz): 8.8 Temperature: -20 to 150F (operating); -40 to 160F (storage) Sealing: Waterproof (submersible) & Fogproof Color/Finish: Non-reflective black with hard coat finish Adjustment (per click): 0.5" at 100 yards Adjustment Range: +/- 40 MOA travel Mount: 1" Weaver Dovetail / Picatinny rail (Mil-Spec 1913) Return to Zero: Repeatable to 1 MOA after remounting MOA: 1 Warranty: 2 Years Heads-Up Display Window Optics Surfaces: Anti-glare and scratch resistant coatings Window Dimensions: 1.20" x 0.85" (30 x 23 mm) Window Material: Shatterproof laminate (3/16" thick) Field of View @ 100 yards: 30 yards (28m) at a 4" eye relief Standard reticle: 65 MOA ring with quadrant ticks with a 1 MOA Aiming dot Reticle Contrast Ratio: 28,000:1 brightest to lowest Night Vision Contrast Ratio: 10,000,000:1 with NV switch engaged Electrical Power Source: 2 x "N" alkaline batteries (available anywhere) Battery Life: 70 hours at normal setting 12 Brightness Settings: 20 settings with scrolling feature Auto Battery Check Indicator: Flashing reticle upon startup if batteries are at 20% of battery life Auto Shutdown: At 8 hours - programmable to 4 hours