Whatman Puradisc 25 mm H-PTFE Syringe Filters 0.45 µm, Hydrophilic, 200 Pack, 6773-2504. Regular Price $301.47 Price $262.15. Add to Cart. Whatman 6894-2504 GD/X 25 mm Syringe Filter, glass microfiber filtration medium, 0.45 um (150 pcs) Regular Price $611.15 Price $531.43. Add to Cart.