1Strong and Durable: The product is made of aviation grade aluminum alloy material, CNC integrated processing technology, so that the fast loading plate has strong robustness. 2Strong Compatibility: The base adopts the standard for 501 plate base compatible for 501HDV, 503HDV, 701HDV, 577, 519, 561, Q5, for Benro S4 S6 and other series head. 3Install and Replace the Base: After attaching the upper for Arca mount base by screws, you can add for Arca mount camera to the head slot using for 501 standard. 4Rich Expanseion: The bottom with 1/4 inch and 3/8 inch screw conversion, can be freely replaced, locking knob has a stop anti loose function. 5Anti Slip Protection: The bottom is equipped with a rubber pad, which can protect the upper base from being scratched, providing a nice equipment for your protection. 1 x Quick Plate Adapter 1 x 3/8 inch Screw 1 x Wrench