A control and closure device for extruded plastically deformable material which is conveyed from an extrusion unit to an outlet nozzle, in which a flange is connected on one side to an outlet opening of the extrusion unit and on the opposite side to the outlet nozzle, and a channel is guided through the flange, through which extruded plastically deformable material can be conveyed from the extrusion unit to the outlet nozzle, and a first piston and a second piston are guided into the channel from two opposite sides; wherein at least one of the pistons (2, 3) is translationally movable perpendicularly to the central longitudinal axis of the channel and/or is mounted and guided rotatably about an axis perpendicular to the central longitudinal axis, and in this case an opening is formed in at least one of the pistons (2, 3) on the outer lateral surface, which opening opens into a channel guided through this piston (2, 3), which in turn opens into a bypass nozzle, or a groove is formed on the outer lateral surface of the at least one piston (2, 3), through which groove extruded plastically deformable material can be conveyed out of the channel in the direction of the outlet nozzle when the piston (2, 3) has been rotated into an angular position in which the groove forms a connection between the channel and the outlet nozzle, through which groove extruded plastically deformable material can be conveyed, and during a translatory and/or rotatory movement of the at least one piston (2, 3), the free cross-section through which extruded plastically deformable material is conveyed in the direction of the outlet nozzle can be varied or the at least one piston (2, 3) is rotatable in such a way that a regulation of the volume flow of the extrudable plastically deformable material conveyed through the channel through the groove is achievable as a result of the angular position of the at least one piston (2, 3) reached in each case, characterized in that when the channel through which extruded plastically deformable material is conveyed in the direction of the outlet nozzle is completely closed, the opening formed on the outer lateral surface of the at least one piston (2, 3) can be positioned in such a way that extruded plastically deformable material can be conveyed in the channel guided through the at least one piston (2, 3) to the bypass nozzle. a channel is guided through the flange, through which extruded plastically deformable material can be conveyed from the extrusion unit to the outlet nozzle, and a first piston and a second piston are guided into the channel from two opposite sides; wherein at least one of the pistons (2, 3) is translationally movable perpendicularly to the central longitudinal axis of the channel and/or is mounted and guided rotatably about an axis perpendicular to the central longitudinal axis, and in this case an opening is formed in at least one of the pistons (2, 3) on the outer lateral surface, which opening opens into a channel guided through this piston (2, 3), which in turn opens into a bypass nozzle, or a groove is formed on the outer lateral surface of the at least one piston (2, 3), through which groove extruded plastically deformable material can be conveyed out of the channel in the direction of the outlet nozzle when the piston (2, 3) has been rotated into an angular position in which the groove forms a connection between the channel and the outlet nozzle, through which groove extruded plastically deformable material can be conveyed, and during a translatory and/or rotatory movement of the at least one piston (2, 3), the free cross-section through which extruded plastically deformable material is conveyed in the direction of the outlet nozzle can be varied or the at least one piston (2, 3) is rotatable in such a way that a regulation of the volume flow of the extrudable plastically deformable material conveyed through the channel through the groove is achievable as a result of the angular position of the at least one piston (2, 3) reached in each case, characterized in that when the channel through which extruded plastically deformable material is conveyed in the direction of the outlet nozzle is completely closed, the opening formed on the outer lateral surface of the at least one piston (2, 3) can be positioned in such a way that extruded plastically deformable material can be conveyed in the channel guided through the at least one piston (2, 3) to the bypass nozzle.