PTFE Membrane Filters, 0.22 um, 25mm, Nonsterile, with PP substrate (Meets the requirements of USP Plastics Class VI) 200 per pack, SF17375. Regular Price $154.67 Price $134.49. Add to Cart. Add to Wish List. PTFE Membrane Filters, 0.22 um, 37mm, Nonsterile, 200 per pack, SF14683.