Review on Neewer Camera Shoulder Rig: Ultimate Film Making Kit for DSLR and Camcorder, Soft Rubber Shoulder Pad, Dual Hand Grips - Compatible with Canon/Nikon/Sony and More (Red + Black) by Mark Crawford

This is a very well built and solid setup but when I shot 2 weddings with it over the weekend I noticed that my Manfrotto 503 (same size) like 501 was ) the removable plate was not attached to the mounting plate of this shoulder mount with a retractable pin, so it does not work properly. After releasing the blue handle on the right side to release the camera, the camera needs to stay fixed on the plate until you press the blue button on the side, but since the camera mounting area is about a millimeter too wide, the blue button does it doesn't work and the camera pops out easily just by pulling the handle. So beware Manfrotto owners, your camera will not be securely attached once the blue button is released and this could result in damage and/or injury to equipment and people! The Neewer quick release plate that comes with the shoulder rest has the same problem - the safety pin doesn't prevent it from slipping out and it's easy to damage your camera. When I contacted the seller about this and took the time to send him a video of it, they replied that they were on vacation and have been scolding me ever since. Not happy with their customer service.