Single board, double board, single column, double column net changer, hydraulic net changer is fast, easy to produce and maintain. With built-in sealing device, the sealing performance is good, which can meet the production of arbitrary high extrusion volume of polymer, and can be used in conjunction with different standard extruders. Fast screen changer time is less than 2 seconds, and filter area is chosen from 30 mm to 250mm. High wear resistance, high pressure resistance, high precision filt