Abstract: A device for influencing the volume flow of extruded plastically deformable material conveyed to an outlet nozzle. A flange arranged between an extrusion unit and an outlet nozzle and is connected to the extrusion unit and the outlet nozzle. A duct from the extrusion unit and the outlet nozzle is incorporated in the flange. A piston is mounted in the flange to be rotatable perpendicular to the longitudinal axis of the duct and is located through the duct. In the piston there is a hole which opens into a bypass duct routed to a bypass nozzle. On the outer lateral surface of the piston there is at least one groove in the region of the duct so that, depending on the angular positions of the piston, material can be conveyed through the at least one groove to the outlet nozzle or through the hole to the bypass nozzle.