The invention relates to a device for axially connecting an external pipe section to a coaxial peg or internal pipe section that engages in the external pipe section, in particular for connecting the drain connecting piece of an injector for injecting fuel into internal combustion engines to a fuel return connector. The external pipe section has two diametrically opposed retaining slots that penetrate the wall of the external pipe section and which correspond to grooves on the periphery of the peg or internal pipe section. Two opposing sprung retaining arms of a clamp-type retaining clip pass through the retaining slots of the external pipe section from the exterior and snap into the grooves of the peg or internal pipe section in a sprung manner. One essential feature of the invention is that the parallel retaining slots of the external pipe section are offset in height in relation to one another, while the whole of the retaining clip, when not fitted onto the pipe sections, lies on one plane.