Standard taper thread couplers are designed to splice the same diameter bars where one bar can be rotated and the bar is not restricted in its axial direction. It is designed to achieve failure loads in excess of 115% of the characteristics stregth of Grade 500 rebar end. Transition taper thread couplers are designed to splice different diameter bars where one bar can be roated and the bar is not restricted in its axial direction. Working principle: 1.Slice up the end of rebar. 2.Make the rebar taper thread cut by taper thread machine. 3.Connect together two taper thread ends by one piece of taper thread coupler.