NcStar 30mm Adjustable Height Ring w/ 1in. Insert 235409. Mounts onto Weaver/ Picatinny/ MIL-STD 1913 type rails. Perfect for use with magnifiers it will allow the shooter to center align the Magnifier with the Reflex Optic Sold as a Single Ring Overall Height: 2.07" - 2.25" Optic Center height can be adjusted from: 1.39" - 1.56" Weight: 2.6 oz. Specifications for NcStar 30mm Adjustable Height Ring w/ 1in. Insert: Manufacturer: NcSTAR Finish: Matte Tube Diameter: 30 mm Ring Quantity: Single Package Contents: NcStar 30mm Adjustable Height Ring w/ 1in. Insert NcStar 235409: 30mm Adjustable Height Ring w/ 1in. Insert