Slide coupling over end of one conduit.
Line up 2nd conduit and mark it to allow coupling to be slid back and centered over both conduits.
Slide coupling back to mark.
Tighten 3/8" hex head bolts and conduits are securely joined together at center of coupling.
Size 1/2 thru 2 inch = one bolt sizes 2 1/2 and larger = 2 bolts at 45 degree angle each end.