Robust 6-screw Tactical Ring is perfect for mounting red-dot optics, magnifiers, and other accessories with 30mm tube diameters to your Picatinny rail. When using this ring to mount a conventional riflescope, we strongly recommend lapping the rings for a proper and secure fit for your optic. This Vortex Tactical Ring positions the center of the riflescope tube at a height of 0.83 inches (21.0 mm) from the base. Sold one ring per package. Backed by our unlimited, unconditional, lifetime, VIP Warranty. A fully transferable promise to repair or replace your item if it becomes damaged/defective. Does not cover loss, theft, deliberate damage or cosmetic damage that doesn't hinder performance.