The firm flexible tube or plastic pipe is pushed onto the integrated connecting sleeve of the 1C connector. The sealing ring forms a tightness for the connection, while it is secured in place by a cutting ring. Due to the knurled nut, this also affects the flexible tube. The cutting ring wedges into the flexible tube or pipe as far as the knurled nut is screwed onto the connector body. A shear force is applied here that intensifies the contact pressure. This creates a friction-locked and tight connection that can be released at any time and minimises the dead volume.