Acratech 2166 Quick Release Plate for Canon 50D / 40D Acratech quick release plates are compatible with all "Arca-Swiss" type quick release clamps (Foba, Arca, Kirk, Wimberly, etc) Acratech quick release plates are camera specific, which means they will fit your camera and will prevent your camera from rotating or moving on the plate Acratech quick release plates are designed to allow access to all camera controls and functions without removing the plate Acratech quick release plates are designed to provide maximum contact area to the bottom of the camera increasing stability and helping to minimize flexing ofthe camera body Acratech does not cut a groove under the head of the mounting screws which weakens them at a point where they are already most likely to break