The Swivel Coupler will fasten from 1-1/4" pipe (1.660" OD) to 2.050" OD truss tube. The Swivel-Coupler has wide wing nuts for fastening the clamp to the pipe or tube. The Swivel Coupler can be locked into a 90 degree fixed coupler by adding an optional 7/32" x 2" spirol pin.