DNZ's Game Reaper is precision machined from a solid block of top-grade billet aluminum and is custom made to fit each type of firearm and align perfectly with your rifle receiver with no moving parts between the firearm and the scope. The Game Reaper absorbs shock and withstands temperature extremes better than steel mounts. Also fits the Remington model 721 and 722 & Bergara B14. Base screws are 6-48 X 1/4 long. Ring screws are 6-40 X 5/8 long. Both use a 7/64 Allen wrench.