Really Right Stuff B82 - J Multiuse Fore-Aft Adaptor Plate
This adaptor plate is in great shape, lightly used.
This 2.6" long anodized 6061-T6 aluminum plate features a sliding 1/4"-20 captive mounting screw for compatibility with a vast number of items as well as an anti-twist flange at the rear to make sure it is secure.
It also features an Arca-type double-dovetail design to mount additional accessories on top of the plate. Additionally, it offers a 1/4"-20 accessory mounting socket and comes with two safety-stop screws for preventing it from accidentally falling off a clamp.