Dosage dispenser device

A dispenser for a viscous product comprising:

• (a) a substantially rigid barrel having an open end and having towards the other end an inner wall partition provided with a passage opening, said barrel being a molded component and defining a compartment for containing the product to be dispensed;
• (b) means defining a discharge passage for said product and adapted to be mounted on said open end of said barrel;
• (c) manually operable push button means at the other end of the barrel and integral with a rack passing through said passage opening, in order to displace said rack between a first and a second position, said rack having teeth;
• (d) a molded piston mounted for sliding in a leakproof manner with frictional contact along the said barrel from the inner wall partition to the open end of the barrel, said piston comprising molded integrally with it:
• sealing lip means adjacent the center of the piston bordering a rack passage and providing a seal between the rack and the piston, said lip means being provided at the lower part of a skirt connected by walls, which converge toward said other end, to a cylindrical wall of the piston;
• catch-engagement means comprising elastic flap means adapted to engage the teeth of the rack, said elastic flap means being convergent toward said other end of said barrel to define a catch engagement lip which is adjacent said sealing lip, said catch-engagement means being effective to impart to the piston the movement of the rack from said first position to said second position, but being flexible so as to move over the rack teeth when said rack moves toward said other end of the barrel, said piston being of a size that said piston is insertable through said open end of said barrel and said rack being insertable through the other end of said barrel and through said passage opening in said piston.