Vector Optics Tomcat Red Dot Sight 1x22x33 Tactical Compact Style, Nonpolar Brightness Adjustment, Red and Green Dot ch Light and Compact, Four Kinds of Reticles, Design for Real Fire Caliber and Ammunition, Tactical Style Magnification 1.0x Tubeless Sight Window Lens Size 22x33mm Mount base length 57mm (2.2 inch) Overall Length 82mm (3.2 inch) Width 65mm (2.5 inch) Height 48mm (1.9 inch) Weight (net) 185g (6.5 ounce) Eye Relief Free Parallax 1 MOA at 80 yards Field of View (M @ 100M) 15.8 Optics Coating Multi Coated Reticle Four kinds of reticles Dot size 5 MOA Elevation Range ±30 MOA Windage Range ±30 MOA Battery Type (Sight) 1pcs CR2032 Stepless green and red illumination adjustment Reticle exchange with audible click Feature 1 M.O.A (50 Yards) windage and elevation Shock proof, Rain Proof and Fog Proof High quality aluminum alloy in durable black matte finish With reticle lock feature Integrated 21mm weaver mount To exchange battery: Use coin to loosen the cap Take out the used battery Exchange with 1 new pc of CR2032 button battery Refasten the cap again