Vortex Optics Precision Matched Rings These Vortex Precision Matched Rings position thecenterof the riflescope tube at a height of 0.97 inches (24.64 mm) from the base. Will only work with Picatinny spec mountswill not work with Weaver mounts. Our Precision Matched Rings are kept in pairs throughout the manufacturing process  ensuring perfection from one set to another. We start with certified USA 7075 T6 billet aluminum and hold it to an extremely tight tolerance of .0005 using our precision Computer Numeric Controlled (CNC) mill. These Vortex rings are serialized, vibratory tumbled, hand-bead blasted and finished off with a Type III hard coat anodize. Sold two rings per package. Hex wrench included. Made in the USA.