Connection device for connection to a first media-carrying component with an external thread, comprising a second media-carrying component with an end connection section, wherein the connection section comprises the following: - a sealing section with a cylindrical outer shell and a sealing element for sealing connection with the end section of the first media-conducting component; - a securing section arranged proximally to the sealing section, wherein an elastic element is arranged on the securing section; a securing piece with an internal thread for screwing onto the external thread of the first media-carrying component, wherein the securing piece and the second media-carrying component are designed in such a way that the second media-carrying component can be connected in a sealing manner to the first media-carrying component with the securing piece screwed on by means of a plug-in process, wherein the connection is secured by the elastic element; the securing section of the second media-conducting component comprises a receiving groove and, as an elastic element, a snap ring arranged in the receiving groove; the securing piece has a tapered inlet for the securing section of the second media-carrying component and a receiving groove for the snap ring of the second media-carrying component in its inserted position; and the tapered inlet of the securing piece has a first taper value in a first section facing away from the receiving groove and has a second taper value in a second section facing the receiving groove, characterised in that the second taper value is greater than the first taper value. a second media-carrying component with an end connection section, wherein the connection section comprises the following: - a sealing section with a cylindrical outer shell and a sealing element for sealing connection with the end section of the first media-conducting component; - a securing section arranged proximally to the sealing section, wherein an elastic element is arranged on the securing section; - a sealing section with a cylindrical outer shell and a sealing element for sealing connection with the end section of the first media-conducting component; - a securing section arranged proximally to the sealing section, wherein an elastic element is arranged on the securing section; a securing piece with an internal thread for screwing onto the external thread of the first media-carrying component, wherein the securing piece and the second media-carrying component are designed in such a way that the second media-carrying component can be connected in a sealing manner to the first media-carrying component with the securing piece screwed on by means of a plug-in process, wherein the connection is secured by the elastic element; the securing section of the second media-conducting component comprises a receiving groove and, as an elastic element, a snap ring arranged in the receiving groove; the securing piece has a tapered inlet for the securing section of the second media-carrying component and a receiving groove for the snap ring of the second media-carrying component in its inserted position; and the tapered inlet of the securing piece has a first taper value in a first section facing away from the receiving groove and has a second taper value in a second section facing the receiving groove, characterised in that the second taper value is greater than the first taper value.