Our most popular filter type, the Standard Cartridge Filter is ideal for most industrial and commercial cleaning applications. Provides filtration of 10 microns @ minimum of 98% efficiency. Fits all Guardair 55, 30 and 20 Gallon Drum Vacuums and Vacuum Generating Heads. For finer filtration, substitute HEPA Cartridge Filter or ULPA Cartridge Filter. 6 pack.