Designed specifically for the HEPA 700, these pre-filters and HEPA primary filter ensure the highest air filtration efficiency. With its standard 2-inch pre-filter and primary HEPA filter media, the HEPA 700 removes dust and other particulates and passes the stringent DOP air filtration tests often required. The optional activated carbon filter with a 1-inch pre-filter and HEPA filter will remove odors, fumes and smoke - especially helpful in wildfire-prone areas.