The Really Right Stuff Sony A7R IV camera body plates are all custom designed to make the most secure fit as possible. Each plate is precision machined from solid blocks of 6061-T6, aircraft grade aluminum. The Sony A7R IV camera plate is fully compatible with any standard 1.5"-dovetail style quick-release system. The plate is also has contoured anti-twist flanges for a perfect fit, which prevents twisting between the Sony A7R IV camera and custom plate. The Sony A7R IV quick release plates utilize a custom machined 1/4"-20 threaded, captive-style mounting screw that threads into the tripod mounting socket of your camera body. As part of a modular system, the Sony A7R IV plate still functions as a traditional camera mounting plate, but also has the added flexibility of accepting a separate dedicated vertical L-component to create a fully modular L-plate with two dovetail mounting surfaces. You can purchase the dedicated vertical L-component as a separate add-on or it is included in the L Set.