This is the Du-Bro 695 2mm Theaded Couplers

Designed for use with DU-BRO Kwik-Links and ball links. One end has no threads and can be soldered on and the other side has 2MM threads

#695 2mm Threaded Couplers are used with DU-BRO' s 2mm Nylon Kwik-Links & can also be soldered on DU-BRO's 2 mm push-rods. The coupler length for this part is 1 1/4 "(31.7 mm).