PTFE (55) PTFE Hydrophilic (23) Polyvinylidene Fluoride (8) Track-etched polycarbonate (9) Whatman PTFE PM2.5 Air Monitoring Membrane Filter, 2.0 µm, 46.2 mm, w/Support Ring, Sequentially Numbered, 50 Pack, 7592-104. Regular Price $557.06 Price $483.77.