bears firmly on the sealing film 60 at the same time the elastomer ring 71 in the area of the housing collar 31 sits sealingly between the cap 81 and the endpiece 20 in the axial direction the elastomer ring 71 is forced in between the axial flank 34 and the sealing film 60 pressed firmly onto the base surface 96 the clamping force of the cap 81 is here generated for example by means of the annular clamping force of the securing area 91 the housing collar 35 serves as an auxiliary abutment when the cap 81 is being fitted in place in small containers in particular it is also conceivable for the cap to engage round the entire container in this case the cap then locks on the base of the container acting as catch element 37 fig3 shows a closure system not part of this invention with a simplified cap 82 this cap 82 does not have the insertion funnel 98 a further variant of fig2 is shown in fig4 not covered by this invention in this variant a depression 25 in the form of an annular channel has been worked radially into the end face 21 the annular channel 25 whose individual cross section is composed of a rectangle surface and a semicircle surface receives the elastomer ring 72 secured to the sealing.