The ProMediaGear CD40 Arca-Swiss Compatible Back-to-Back QR Clamps includes two 40mm wide clamps, with one-1/4-20 insert, one 3/8-16insert, mounting screws for inserts, mounting screw for clamps, wrenches and 2 pins. Hard coated black anodized surface.
Nickel-chrome plated insert, this ensures that threads will remain in good condition almost indefinitely, as opposed to all other designs that have threads cut directly in the aluminum body of the clamp, rending it useless once the threads wear out in the aluminum. These can be used for paralax offset and other slide the rail applications, or separately.
These are precision machined instruments and even when screw is removed from clamps they will stick together just on the pins, because its really a tight fit, to pull them apart you have to pull very evenly, as there is almost no play, also when mounting back please don't forget to use the big screw to secure both clamps together.