when the male part is arranged in the female part and the locking device is activated ie the annular bead 19 is enclosed by the annularly extending recess 20 on the outer face of the male part and that the annularly extending flange 23 og the male part is situated in the annular recess of the female part and wherein the medially facing delimiting face 25 u2032 of the flange 23 presses against the laterally facing side of the medially delimiting wall of the annular recess whereby a sealing occurs in that area simultaneously with a pressing occurring between bead 19 and the annular recess 20 hereby forceful sealing is ensured and likewise the delimiting edge 26 of the flange presses upwards into the bottom of the annular recess and thus ensures yet a sealing fig8 shows the use of a connecting piece 1 wherein a leg bag 34 is connected to the leg of a patient and in the upper part there extends a catheter 36 from this leg bag for collecting urine said catheter being connected to the urethra of the patient opposite the area where the catheter 36 is connected the urine bag 34 is provided with a tubing element 6 this tubing element is further connected to a connecting piece 1 according to the invention the tubing element is mounted to the first connecting element of the first unit which is configured as a stub on the stub 35 of the male part there is also mounted a tubing 2 that is connected to a discharge collector receptacle 37 when the leg bag 34 of the patient is thus filled the discharge bag 37 will typically be mounted with the tubing 2 on which the male part is.