1. Slide-stopping rubber mats to prevent the camera/lens from moving while changing the position of the head. 2. Patented SIRUI safety lock design, that prevents your camera from accidentally sliding off of the head when you slightly loosen the Quick Release Clamp (to make adjustments to the positioning of your equipment). 3. Arca-compatible 4. Red anti-twist stoppers prevent the camera from shifting or twisting when you move your camera in a vertical position. Pop up the stoppers before attaching the SIRUI QR plate to your camera, and they do all the work!