The RRS-9000515 by Really Right Stuff was was specifically designed for use with Leupold's line of Mark 4 and Gold Ring Spotting Scopes, and is precision machined from a solid block of 6061-T6 Aluminum. The RRS-9000515 is fully compatible with all Arca-Swiss type quick release systems, and is equipped with a precisely machined anti-twist key for a seamless fit which prevents twisting between the scope and the plate. Like all of Really Right Stuff's plates, the RRS-9000515 is outfitted with a custom machined 1/4"-20 threaded, captive-style mounting screw which threads into the scope's tripod mounting socket. Features of the RRS-9000515:CNC machined 7075-T6 AluminumAnodized; Type III BlackFits Leupold standard mounting socket and key slot1/4"-20 threaded mounting holeAnti-twist key fits both primary body mount and extended body mount Really Right Stuff BLPD Leupold Spotting Scope Foot Plate RRS-9000515 in Black