Whatman 6888-2527 Glass Microfiber GD/X 25 Syringe Filter, GF/D, 25mm, 2.7 Micron (Pack of 150) 2.7m; ideal choice for the preparation of hard-to-filter samples Pigment-free polypropylene housing with a prefiltration stack Eliminates sample contamination Allows you to filter even the most difficult samples with less hand pressure Processes three to seven times more sample volume