Optic Shim is made to fit between the red dot and the mounting plate. All trademarks mentioned belong to their respective owner, this optic shim is made by ADE as a mounting accessory for the mentioned opticsWhat it does? While zeroing the red dot sight, some users turned the elevation screw all the way to the end that can no longer turn(screw maxed-out), the location of the illuminated dot is still TOO HIGH, user is UNABLE to adjust the dot LOW enough to zero. Instead of returning the "defective" red dot, this shim will rise the optic to help user to move the illuminated dot higher to the location to zero. Scope base shims Tolerance +/-.005 Taper 1.0 degree. Also Fits: Ade Advanced Optics RD3-006, RD3-009, RD3-011, RD3-012, RD3-013, RD3-015. Also Fits: Ade Advanced Optics RD3-006, RD3-009, RD3-011, RD3-012, RD3-013, RD3-015. The center two screw holes might be 1 or 2mm off for some red dots, if so, simply trim cut the hole bigger. Does NOT fit Trijicon rmr, Shield, Sig Romeo, Holosun red dots. Fits: Burris Fastfire II, III, Docter Red Dot Sight & Insight MRDS. Optic Shim is made to fit between the red dot and the mounting plate. Depending on the handgun, some handguns need THIS 1degree shim to give extra range of elevation across a wide range of firearms (such as the 1911). Should you feel any resistance from the mechanism whilst zeroing the elevation please fit the shim between the sight and the mount with the thickest part at the rear.Night vision: No. Mounting Type: Picatinny Mount. Compatible Devices: Handgun. Sport Type: Hunting. Color: Black. Brand: Ade Advanced Optics. Date First Available: September 19, 2019. Best Sellers Rank: #246,019 in Sports & Outdoors. Customer Reviews: 3.2 out of 5 stars 17 ratings 3.2 out of 5 stars. : B07Y3THRGL. Sport Type: ?Hunting. Part Number: ?OpticShim-1. Manufacturer: ?Ade Advanced Optics. Color: ?Black. Brand Name: ?Ade Advanced Optics. Package Weight: ?0.01 Kilograms. Item Package Dimensions L x W x H: ?7.2 x 2.7 x 0.1 inches.