Fits Savage Flatback Receiver (Fits 2003 and older long and short actions) : Front of receiver is rounded and back is flat where mounts attach. 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. Hole spacing dimensions on front and back mount are .86?. Both mounts are not the same part. Back mount is taller than front mount because receiver is lower on back end. Standard rings are .63? wide and Tactical rings are .80? wide. Standard rings have 2 screws per ring and Tactical rings have 4 screws per ring. Height of mounts from top of receiver to centerline of scope tube is - low .92?, medium 1.05?, and High 1.17?. 4 screws