Corning® 1000 mL Vacuum Filter/Storage Bottle System, 0.22 µm Pore 54.5cm² PES Membrane, Sterile, 12/Case Polyethersulfone (PES) membranes provide the fastest flow rates, the lowest protein binding and low extractables and are best for filtering cell culture media. 1000 mL receiver bottles feature easy grip sides for improved handling.