Immunity Machine 8 Phase Replacement Filter This is a replacement filter for the Austin Air Immunity Machine Air Purifier. It can also be used to upgrade any standard model Austin Air purifiers, including the HealthMate, HealthMate Plus, and Bedroom Machines. This primary replacement filter includes a medium particle filter, a four-part granular defense combo of carbon, impregnated carbon, mineral-based filtration, and impregnated mineral-based filtration, True Medical Grade HEPA filter, and Military-Grade HEGA Cloth. Replace approx. every 5 years. It comes in two colors: black and white. Use the Black filter with black, graphite, and midnight blue colored air purifiers, and the White filter for white and sandstone colored air purifiers. When replacing the primary filter, use in conjunction with a replacement large particle pre-filter. [tabs]