Corning 250mL Vacuum Filter/Storage Bottle System, 0.45µm Pore 19.6cm² CA Membrane, Sterile, 12/Case: 157-0045: SFCA 250ml, Filter Unit, 50mm Diameter Membrane; 0.45um: 430521: Corning 500mL Bottle Top Vacuum Filter, 0.22µm Pore 33.2cm² CA Membrane, Fits 33mm Diameter Necks, Sterile, 12/Case : 291-3320