Abstract: A coupling comprising a male and female half (11, 12) that are coupled together in axial alignment. A keying portion (13) is provided at one end of the male half (11) which has at least one keying element (14) with a bearing surface (20). The female half (12) has an opening (17) located on one side with recesses (18) therein shaped for location of the keying element (14). The opening (17) allows the keying portion (14) to engage the opening (17) in a direction that is transverse to the aligned axis. The recess (18) has abutment surfaces (21) against which the bearing surfaces (20) locate when the keying portion (14) is engaged within the recess (18). The bearing (20) and abutment (21) surfaces prevent separation of the coupling when placed under tension along the aligned axis. The invention provides a simplified means for connection of the coupling while at the same time allowing relative rotation between the male and female halves (11, 12).