Acratech 2150 Quick Release Plate for the Contax 645 AF and Mamiya RB, RZ / Non AF 645 without the Winder. Acratech quick release plates are designed to allow access to all camera controls and functions without removing the plate. Acratech quick release plates are designed to provide maximum contact area to the bottom of the camera increasing stability and helping to minimize flexing ofthe camera body. We do not cut a groove under the head of the mounting screws which weakens them at a point where they are already most likely to break. Our plates are precision C.N.C. machined from solid 6061 T-6 aluminum. We do notuse inferior castings like some manufacturers. Made in the U.S.A.