All calibers made on same action, Mount fits both left and right hand firearms. Outside to outside of rings is 4.14 inches. Standard rings are 0.63 inches wide and have 2 screws per ring 0.4 hole to hole spacing dimensions are 0.86, 3.19, 0.86 inches. Features: Precision machined from a solid block of top-grade billet 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 1-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 Normal action Made in USA