Precision machined from a solid block of top-grade billet 6061T6 aluminum. Custom made to fit each type of firearm and align perfectly with your rifle's receiver. No moving parts between the firearm and the scope. 67% lighter than comparable one-piece mounts with four times the threads and precision socket-head cap screws for absolute strength and security. Absorbs shock and withstands temperature extremes better than steel mounts at a fraction of the weight. Made in the USA.