Manfrotto 3433PL 577 Rapid Connect Adapter with Sliding Mounting Plate
Compatible  with the 501PL camera plate (supplied with the head 501HDV, 503 and 519 Video Heads) and the special 501PLONG accessory plate. This Quick Release adapter gives you the freedom to remove the camera from the head without detaching it from the plate and put it on any other support. Supplied with 1/4'' and 3/8'' camera screws.Technical Specs:Attaches by1/4" or 3/8" attachment typeAttachment3/8" female thread attachment typeMaterialAluminumPlate Type501PLSecondary Safety SystemYesSliding Travel of Plate20.0 mm • 0.79 inWeight0.28 kg • 0.62 lbs