The Holographic Weapon Sight (HWS) EXPS3 is an excellent choice for professionals. The EXPS3 offers true two eyes open shooting for fast target acquisition, night vision compatible settings, and a 7mm raised quick detach base for lower 1/3 iron sight co-witness. Specifications: Dimensions: 3.8" L x 2.3" W x 2.9" H Weight: 11.2 oz Water Resistant: 33ft Depth Mount: 1" Weaver or MIL-STD-1913 Rail Windage and Elevation Adjustment: 0.5 MOA per Click Brightness: 20 Daylight settings; 10 Additional Settings for Gen 1 Through Gen 3+ Night Vision Devices Power Source: 1x CR123 Battery Battery Life: 1,000 Continuous Hours at Norminal Setting 12 at Room Temperature Operating Temperature: -40Adeg F to 140Adeg F Country of Origin: USA Reticle: Eotech Four Dot Reticle Use this ballistic reticle with 5.56 Nato/.223 cal with 62gr M855 FMJ at roughly 2,680 fps with a 14.5" barrel. Aiming dots on the 4-dot reticle may not be distinguishable without magnification.