a plastic closure including a bottom part and a lid that has an annular retaining bead in the bottom part . a disk having a support surface is held positively or non - positively in the bead . the disk includes one or more through - passages , which open into a chamber . a thixotropic fluid present in a flexible container reaches the chamber through the through - passages , where the fluid performs a directional change from axial to radial and after a second directional change from radial to axial flows out through the spout opening , wherein a constriction between the two directional changes accelerates the flow .