CVA Rifle (All 2010 and newer break open black powder barrels and all years of center fire rifle barrels)/li>Precision machined from a solid block of top-grade billet aluminumCustom made to fit each type of firearm and align perfectly with your rifle?s receiverNo moving parts between the firearm and the scope67 percent lighter than comparable one-piece mounts with four times the threads and precision socket-head cap screws for absolute strength and securityAbsorbs shock and withstands temperature extremes better than steel mounts at a fraction of the weightBase screws are 8-40 X 1/4? long. Ring screws are 6-40 X 5/8? long. Base screws use a 9/64? Allen wrench and ring screws use a 7/64? Allen wrenchOutside to outside of rings is 3.92?. Rings are .63? wide. 4 Hole to hole spacing dimensions are .86? 79? .86?. Height of mounts from top of barrel to centerline of scope tube is ? low 1.00? medium 1.13? high 1.25? and X High 1.38?Made in the USA