faces 84 and the plugging axis 14 is greater in the illustrated example the angle u03b2 is approximately 25 u00b0 to 35 u00b0 in particular approximately 30 u00b0 and the angle u03b3 is approximately 70 u00b0 to 80 u00b0 here the latching step 32 is preferably also constructed within the connector counterpart 2 as an oblique face in such a way that in the release position of the locking element 34 the plug in connector 1 can be released in a frictionally locking fashion by simply pulling it out by virtue of the fact that the latching shoulders 30 are moved radially inward over the respective oblique faces furthermore it is advantageous if the plug in connector 1 has in the junction region between the plug in section 4 and the conduit connection section 8 a stop element 86 or one on each diametrically opposite side against which the locking element 34 moves axially into abutment in its upper release position the stop element 86 therefore forms an end stop for upwardly limiting the movement of the locking element 34 in the release direction as a result a release force can advantageously also be applied to the plug in connector 1 via the locking element 34 by means of a lever like tool screwdriver in order to downwardly limit the axial movement of the locking element 34 in the plugging in direction in the secured position see in particular fig3 the plug in connector 1 has in each case two stop knobs 58 u2014 in turn preferably symmetrical on the two diametrically opposite sides u2014 on.