PTFE Unlaminated Membrane Filters, Hydrophilic, 0.5 Micron, 25mm, 100/Pk (H050A025A) Durable, efficient, and broadly compatible, these pure, hydrophilic PTFE membranes are ideal for use with HPLC seperations, aqueous/organic solvents, and many of your other filtration needs. Pack of 100. Pore size: 0.5 microns.