Tisch Scientific PTFE Disk Filter, 0.1 µm, 50 mm, Stepped Barb: 5/16 to 1/2, Nonsterile, 10 Pack, DF17076. Regular Price $46.79 Price $40.68. Add to Cart. Add to Wish List. Tisch Scientific PTFE Disk Filter, 1.0 µm, 50 mm, Stepped Barb: 5/16 to 1/2, Nonsterile, 10 Pack, DF17049. Regular Price $46.79 Price $40.68.