This type of couplers are used to splice bars with different diameters. They are also called as Transition Couplers. The reducer coupler is rotated onto the bar with higher diameter and then the bar with lower diameter is rotated from other end for joining. Reducer couplers can have parallel threading as well as tapered threads.

Mechanical Splicing becomes easy in cases of steel congestion due to long lap splice

Reducer couplers enables continuous reinforcement and develops UTS independent of concrete and greater than the parent Rebar.