PNC ATP-ANTI TWIST PLATE For MANFROTTO 501PL Canon EOS 5D Nikon D800 FIT The Manfrotto 501PL Quick Release plate is compatible across several of Manfrotto's Video Fluid Heads making it highly popular among DSLR Video Shooters. The 501PL (or compatible) quick release plate offers an anti-twist register pin, but the design of DSLR camera bodies are unable to take advantage of this. The ATP is designed to 'LOCK' in place above the 501PL plate and adds an anti-twist lip across the camera body. The ATP is designed from hard molded plastic to prevent wear against your camera body, and offers a non-slip durable rubber padding that further grips your camera's underbody when mounted. 14-day money back guarantee, 1 year manufacturer warranty