Desmond D2X30 30mm Dual Double Subtend Clamp Arca Compatible Under & Over Under and over independant Arca clamps. will accommodate any Arca style plate from various makers including: Really right stuff (RRS), Wimberley, Arca Swiss, Kirk Enterprises, Markins, etc. 30mm (1.2") in Length. 3/8"-16 thread with metal 1/4"-20 Adapter Weighs just 94g (3.3oz)