The hs403r is a small compact micro red dot optic that features holosuns new rheostat dial to adjust brightness settings.The hs403r can achieve a constant "on" battery life of up to 100,000 hours! it has a 2 moa dot size, unlimited eye relief, unlimited field of view, and has a ip67 waterproof rating.A low mount and 1/3 co-witness mount is included.Battery: CR2032 LithiumMagnification: 1xField Of View: UnlimitedEye Relief: UnlimitedDot Size: 2 MOATube Diameter: 20mmLength: 2.75"Weight: 3.53 ozFinish: BlackReticle: 32 MOA Ring/Red DotAdjustment Size: .5 MOAProofs: Water Resistant, ShockproofOptic Coating: Multi-Coated