Adapter for Arca-Swiss Quick Release Plate to Manfrotto RC4 Tripod Head Clamp | eBay
Amazon.com : SIOTI 323 RC2 Quick Release Plate Adapter, Rapid Connect Adapter with Quick Release Plate for Man frotto Monopod, Manfrotto Tripod, or Other Ball Head and Tripod : Electronics
Hexagonal Adapter Plate normal with 1/4'' screw - 030-14 | Manfrotto Global