Minisart® SRP15 Syringe Filter 17558----------K, 0.2 µm hydrophobic PTFE. Minisart ® SRP with chemically inert hydrophobic PTFE is suitable for venting as well as harsh solvents with a pH of 1 - 14. Type 17558 with a pore size of 0.2 µm can be used for sample preparation and sterile filtration and has a male spike outlet.