Whatman 6871-2504 GD/X 25 mm Syringe Filter, nylon filtration medium, 0.45 um (1500 pcs) Regular Price $2,733.72 Price $2,374.02. Add to Cart. Whatman Puradisc 25 mm PVDF Syringe Filters, 0.45 µm, 50 Pack, 6746-2504. Regular Price $171.00 Price $148.50. Add to Cart. Whatman Puradisc 13 mm Nylon Syringe Filters, 0.45 µm, 500 Pack, 6790-1304.