pressure container the user can actuate the closure device by pressing on the upper frontal wall 72 of the cap top wall 41 with the tip of the finger lying in recess 71 thereby the outlet valve of the pressure container 67 is depressed and thus moved out of the closed position shown in fig1 into the discharge position of fig1 thereby the product preferably in form of a foam or optionally of a paste is expelled by the pressure in container 67 into the discharge duct 43 on penetrating into the region 43c of the latter duct the product assisted optionally by a portion of propellant discharged ahead of it raises the elastically flexible wall zone 46 so that the contact edge of this zone lifts off from the orifice edge 45a of the rigid wall zone while simultaneously lifting the lip 47c and tensioning the elastically flexible arm 47b of the beak member 47 whereby the flexible wall zone 46 snaps out of the convex contact position along the rigid contact edge 45a into its opposite concave position with a correspondingly chosen material e g polyethylene no upsetting deformation of the elastically flexible zone edge occurs during the transition but rather an s shaped deformation as a transitional stage to the concave position as soon as the finger of the user releases the cap top wall 41 the latter returns under the pressure of a return spring member not shown always provided in the valve of the pressure container out of the open position of fig1 back into the closed position of fig1 thereby the excess pressure prevailing in the discharge duct 43 drops immediately and the lip 47c of the arm 47b of the beak member 47 presses the elastically flexible wall zone 46 at.