Medical Millex-GP Syringe Filter Unit, 0.22 µm, polyethersulfone, 33 mm, sterilized by gamma irradiation. A 33 mm diameter sterile syringe filter with a 0.22 µm pore size hydrophilic Polyethersulfone (PES) membrane. Comes in a pack of 50. A 25 mm diameter sterile syringe filter with a 0.22 µm pore size Polyethersulfone membrane.