Desmond DBI-60 Bidirectional Double 90&deg; Degree QR Clamp Arca-Swiss Compatible for Tripod Ball Head 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. Precise 90 Degree angle 3/8"-16 thread with metal 1/4"-20 Adapter All metal construction.