Abstract: A coupling comprises a sleeve shaped member (5) which has an external toothing (11), an internal threading (12) and also a tubular guiding portion (13). An annular member (14) surrounding the toothing (11) is rotatably mounted over the sleeve shaped member (5) and has a handle (28) and a reversible catch (22) to engage the toothing. A coupling member (29) to be threadingly connected to the sleeve shaped member (5) has for that purpose an external threading (30) as well as a saw tooth shaped, peripheral bead (31) to obtain a guide function by cooperation with the tubular guiding portion (13). A further coupling member (1) is rotatably but non-displaceably connected to the sleeve shaped member (5) and has in the end surface thereof a groove (3) having a dovetail section and an O-ring (4) inserted thereinto.