<p>The plug-in unit (1) in combination with the pipe (2) is inserted into a case (G). The elastic rubber seal (11) has a sealing lip (15) positioned at the outer edge, pre-tensioned with the inner radius of a bore of the case, and a second sealing lip pointing to the pipe, pre-tensioned with the surface of the pipe. When both parts are joined, the seal slips into a circular groove (9) inside the plug-in unit preventing disconnection.</p>
