A coupling device for releasably connecting fluid-carrying duct ends of ducts is provided. The duct ends, respectively, each carry a jacket having at least two annular ribs housing a first annular sealing element. The first annular sealing element is engaged by the inner shell. The coupling device includes an outer shell that has radially inward extending ribs or rib portions, which are either arranged in an axial distance with respect to a further annular rib of the jackets or engage an axial recess provided on the jackets defined between the further annular rib and a fourth annular rib.