Whatman Puradisc 25 mm PTFE Syringe Filters, 0.2 µm, 50 Pack, 6784-2502. Regular Price $189.24 Price $164.34. Add to Cart. Add to Wish List. Whatman 6869-2502 GD/X 25 mm Syringe Filter, nylon high charge (positive), nylon filtration medium, 0.2 um (150 pcs) Regular Price $539.90 Price $468.86.