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 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 With the new Nikon Prostaff P3 shotgun scope you will need the high 12200OS mount, the focus ring is larger and you have to have a taller mount to keep it off the base Mount fits both left and right hand firearms Receiver is rounded on front and back of receiver where mounts attach MOA mounts are tapered down on front for long range shooting, height will be about 0.03 inches lower on front ring than a standard straight mount Base screws are #6-48 x 1/4 inches long and ring screws are #6-40 x 5/8 inches long, both screws use a 7/64 inches allen wrench Some of the Stealth models and 338 Lapua receivers have been modified at the factory and have larger base screws Outside to outside of rings is 4.36 inches Made in the USA