Rebar coupler also is  named rebar connector, steel bar coupler, reinforcing bar coupler, mechanical rebar coupler,  is for connecting rebar together, used in reinforced concrete construction.

Rebar splice system included 3 type:

Rolling technology type, Upset forging technology type ,Cold pressing technology type .

Rolling type rebar coupler, with parallel threads, the end of Rebar Threads are rolled, so that the threaded portion has a diameter equal to the parent bar. then the threaded ends are screwed into the coupler.

Upset forging type rebar coupler , with parallel threads, the end of rebar threads are  first forged, enlarged, then cut into threads, so the threaded portion has a diameter larger than the parent bar, then the threaded ends are screwed into the coupler.

Cold pressing type coupler are no thread, threadless coupler, put end of rebar into threadless coupler, then press rebar and coupler together by rebar cold extrusion pressing machine.