Precision machined from a solid block of top-grade billet aluminum; Custom made to fit each type of and align perfectly with your 's receiver; No moving parts between the 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; For scopes with 3" to 4" eye relief; Base screws are 6-48 x 1/4" long; Ring screws are 6-40 x 5/8" long; Both screws use a 7/64" Allen wrench; Outside to outside of rings is 4.55"; Standard rings are .63" wide and have 2 ring screws per ring; Made in the USA