The compact single-piston screen changers SSC from maag pump systems provide an alternative for extrusion applications which allow for interruptions in the melt stream during screen changeover. SSC operate without any additional seal and their sturdy construction guarantees reliable and leak-free filtration of polymer melts. The rheologically optimized flow channel directs the melt flow optimally and with a short residence time into the screen cavity. The breaker plate is fitted with screen mesh suitable for the required filtration size. The screen changer is operated by a hydraulic piston.