The invention concerns a coupling for use in forming a sealed joint between first and second tubular members. The coupling provides a through-passage defined by an inner coupling face and having a first open end for insertion of the first tubular member into a first region of the through-passage and a second open end for insertion of the second tubular member into a second region of the through-passage. A first inwardly directed engagement recess is provided in the inner coupling face in the first region of the through-passage and a second inwardly directed engagement recess is provided in the inner coupling face in the second region of the passage. In the assembled joint, the first inwardly directed engagement recess aligns with a first outwardly directed engagement recess of the first tubular member to form a first channel for receipt of a first retainer to secure the first tubular member in the coupling. The second inwardly directed recess aligns with a second outwardly directed engagement recess of the second tubular member to form a second channel for receipt of a second retainer to secure the second tubular member in the coupling. The first region of the through-passage has a larger diameter than the second region of the through-passage.