Abstract: A dispenser capsule for liquid or paste products comprising an element slng in a tubular envelope between an open raised position and a closed retracted position, via a maneuvering thruster for respectively disengaging or blocking a flow opening of the product contained in the receptacle on which the capsule is mounted. The capsule comprises a cowl which is adapted to be mounted on the neck of the receptacle and which is affixed to the envelope in which is slidably mounted a piston guided axially by the envelope and by a chimney also affixed to cowl, the chimney communicating by one end with the opening of neck of the receptacle, its other end having an opening which is reduced with respect to that of the neck and in communication with said flow opening when piston is in a raised open position. The piston comprises a top and a lateral wall forming the maneuvering thruster and wherein the envelope is provided with a recessed portion enabling access to the thruster for its activation.