PTFE Membrane Filters, 0.22 um, 25mm, Nonsterile, with PP substrate (Meets the requirements of USP Plastics Class VI) 200 per pack, SF17375. Polytetrafluoroethylene PTFE Membrane Filters, 0.22um, 25mm, Nonsterile, with PP substrate (Meets the requirements of USP Plastics Class VI) 200 per pack. Regular Price $154.67 Price $134.49. In stock. SKU.