Howa 1500: Mounts fits right hand firearms. 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. Short action – Outside to outside of rings is 4.17″. Standard rings are .63″ wide and have 2 ring screws per ring. Tactical rings are .80″ wide and have 4 ring screws per ring. 4 Hole to hole spacing dimensions are .86″, 3.88″, .60″. Height of mounts from top of receiver to centerline of scope tube is – low .98″, medium 1.11″, and high 1.23″. Long action – Outside to outside of rings is 4.61″. Standard rings are .63″ wide and have 2 ring screws per ring. Tactical rings are .80″ wide and have 4 ring screws per ring. 4 Hole to hole spacing dimensions are .86″, 4.48″, .60″. Height of mounts from top of receiver to centerline of scope tube is – low .98″, medium 1.11″, and high 1.23″. Same mount used on the Weatherby Magnum and Weatherby Vanguard. 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. Made in the USA.