Stericup Quick Release-GP Sterile Vacuum Filtration System, 250 mL process volume, 0.22 µm pore size, polyethersulfone membrane, pkg of 12, radio-sterilized S2GPT05RE Steritop Quick Release, Sterile 500 mL Steritop Quick Release-GP 45 mm threaded bottle top filter with 0.22 µm pore size fast flow polyethersulfone (PES) Express PLUS membrane.