Holmes HAP9422-NUA aer1 HEPA-Type Tower Air Purifier Nullify Imported HEPA-Type filtration, Filter service indicator reminds you when filter needs replacement 3 speed settings provide options for different conditions Optional Ionizer assists in particle removal Recommended for medium rooms, up to 165 sq ft. Smoke CADR: 105 Filters: Any AER1 Series, Holmes HAPF30D-U2 HEPA Type or Holmes HAPF300D-U2 TRUE HEPA Filter