UTG 3X Magnifier with Flip-to-side QD Mount, W/E Adjustable Broadband Multi-coated Lens to Provide Crystal Clear 3X Image, Wide Field of View - 30% Bigger Than Comparable Models from Other Brands.Compatible Rail-Picatinny/Weaver. Windage/Elevation Adjustability for Optimum View Centering. Refer user manual for list of compatible manuals 42mm Center Height for Most Common Dot Sight Combination, Innovative Flip-to-Side Mechanism for Quick Transition between 1X and 3X Image.Objective Diameter:25mm;Field of View @ 100 yards:45' Adjustable Eyepiece for Easy Dioptric Correction, Patented Quick-detach Lever Lock Mounting Base Precision Machining and Anodizing for Maximum Strength and Wear Resistance, Completely Sealed and Nitrogen Filled for Fog/Weather Proof