The invention relates to a coupling comprising a first (3, 3′) and a second (5,5′) coupling part being adapted for coupling together and uncoupling along a centre axis (CL) extending through the coupling (1), an outer surface (7) of the first coupling part (3, 3′) comprising at least a recessed helical slot (9), an inner surface (11) of the second coupling part (5, 5′) having at least one projection (13, 13′, 13″) extending inwards for engagement with the said slot (9). The second coupling part (5, 5′) comprises a lock socket arrangement (17, 19) being displaceable relatively to its rear portion (15) along a centre line (CL) and having an inwards projecting portion (23, 23′, 23″), at least one lock body (25, 25′, 25″) arranged in the second coupling part (5, 5) being movably arranged relatively to the lock socket arrangement (17, 19) and by means of retention means (27, 27′) being connected to the rear portion (15), the outer surface (7) comprising a collar (29) for receiving the lock body (25, 25′, 25″) affected by the projecting portion (23, 23′, 23″) at the said coupling together.