A coupling (1) for receiving at least two plug-in connectors (2) which are joined to glass fiber cables, comprising at least one moveable cover (14) which is associated with a sheath opening (121), said cover covering the opening (121) of the sheath in a first position, and being able to be moved into a second position by introducing a plug-in connector (2), whereupon the cover (14) releases the opening (121) in the sheath, said cover (14) comprising a bent metallic leaf spring (141) and said leaf spring (141) being unstressed in the first position and the curvature of the leaf spring (141) being selected in such a way that a ferrule (23) of the plug-in connector (2) never comes into contact with the leaf spring (141) during the insertion process.