Wimberley offers a line of Arca-Swiss style quick-release plates for collared lenses. The Wimberley P-40 Arca-style lens plate has important innovative features that distinguish it from other plates on the market. Dual Safety Stops at the front and back of the plates, keep your expensive lens from accidentally slipping out of the quick-release clamp. If you wish to use only one or neither of these stops, simply remove them with the hex key provided. Note: The two stop screws will straddle the length of most quick-release clamps.