Abstract: A co-axial plug has a cylindrical outer-conductor part having mating co-axial cable ends. A latching sleeve fits around and is axially displaceable relative to the shell outer-conductor. Opposite ends of a spring are supported against the shell outer-conductor part and the latching sleeve to pre-load the latching sleeve toward the co-axial cable end of the shell outer-conductor part. Axial slots at the latching sleeve mating end form elastically resilient latching tongues having, at their ends, a latching edge extending in a radially outward direction. An unlocking sleeve surrounding the latching sleeve is displaceable axially relative to the latching sleeve having a ramp extending outwardly and sloping toward the cable end. The ramp co-operates with a correspondingly bevelled groove on the unlocking sleeve inside face so displacement of the unlocking sleeve relative to the latching sleeve toward the co-axial cable end bends the latching tongues inwardly.