The 501PL Quick Release Plate has 3.38" long sliding quick release plate compatible with heads that use the RC5 quick release system. It comes supplied with one 1/4"-20 and one 3/8" camera screw each, and features a location (video) pin. For 501, 503 & NG Heads RC5 Quick Release System. Replaces #3433PL. NOTE: The item is not a manfrotto brand. Its quality is almost as good as manfrotto.