Ring mounts attach directly to the receiver, offering a rock solid ring and base combination that eliminates any seams between the gun and scope. Made from lightweight aluminum so they are 1/3 the weight of other mounting systems. Notes:Socket head cap screws included for mounting to firearmEach mount is specifically machined to fit the particular firearmRing heights vary depending on the specific firearm and base machining. Please use the average height to select the correct height for mounting.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. Ring height (bottom of base to bottom of ring):Low, .437" to .500", average .469"Medium, .562" to .625", average .594"High, .687" to .750", average .719"