Oct 29, 2021 · The 50 mm Millex® filter units are especially useful for vacuum line protection. All units are bi-directional. A 25 mm diameter sterile syringe filter with a 0.2 µm pore size hydrophobic PTFE membrane, ethylene oxide sterilized. Ideal for sterilizing gases, venting sterile containers, and sterilizing or clarifying organic solutions.