Abstract: A first quick-coupling member (1) is adapted for introduction into and removal from a recess (2a) situated in a unit which can cooperate with the first coupling member, for example a second coupling member (2). A protective sleeve (4) is disposed on a body surface (1d, 1e) present at the front portions of the first coupling member. The protective sleeve is longitudinally displaceable in the longitudinal direction of the first coupling member, besides which the external diameter (d3) of the protective sleeve exceeds the internal diameter (D3) of the recess. In an initial position, the protective sleeve is conveyed forwards towards the front end (1c) of the first coupling member where it prevents the access of impurities to the front portions (1d) of the body surface. When the first coupling member is introduced into the recess, the protective sleeve is displaced longitudinally backwards on the first coupling member to expose its parts (1b) which is introduced into the recess.