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 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 Browning X Bolt: Base screws are 6-48 X 1/4" long. Ring screws are 6-40 X 5/8" long. Both screws use 7/64 Allen wrench. Super Short action ? Outside to outside of rings is 3.79". Rings are .63" wide. 4 Hole to hole spacing dimensions are .70", 2.82", .70". Height of mounts from top of receiver to centerline of scope tube is ? low .94", medium 1.06", and high 1.19". Mount fits right hand firearms. Long action ? Outside to outside of rings is 4.58". Standard rings have 2 screws per ring and rings are .63" wide. Tactical rings have 4 screws per ring and are .80" wide. 4 Hole to hole spacing dimensions are .70", 3.69", .70". Height of mounts from top of receiver to centerline of scope tube is ? low .94", medium 1.06", and high 1.19". Mount fits right hand firearms.