PTFE Laminated Membrane Filters, 0.45 Micron, 300 x 300mm, 5/Pk. PTFE Laminated Membrane Filters, 0.45 micron, 300 x 300 mm, pack of 5 sheets. Hydrophobic, durable ePTFE laminated on to a polypropylene later. Ideal for venting, phase seperations, and aerosol sampling.