Weatherby Mark V standard receiver: Look at hole to hole dimensions below before ordering. Your firearm might be made on a different receiver. Mounts fit right hand firearms. Base screws are 6-48 X 1/4 long and ring screws are 6-40 X 5/8 long. Both screws use a 7/64 Allen wrench. Outside to outside of rings is 4.44. Standard rings are .63 wide and have 2 ring screws per ring. 4 Hole to hole spacing dimensions are .86 4.28 .60. Height of mounts from top of receiver to centerline of scope tube is - low .94 medium 1.06 and high 1.19.