Whatman 10443421 ZapCap Cellulose Regenerated Bottletop Filter Unit, Nylon Membrane, 0.2 Micron, 500ml Volume (Pack of 12) 4. Quick look. price. $246. . 56. Autofil PP - Disposable Vacuum Bottle Top Filters for Solvent Filtration, with 0.45um PTFE Membrane for Clarification and Prefiltration, 500mL, GL45 Thread Housing, Non-Sterile, (Pack of 12