G-7 Whole House Air Purifier System Anion (negative ion) generator: Restores healthy ion balance to drop lung damaging particles out of the air. UV/UVC Photo Catalyst Chamber: Most advanced sterilizer--should run continuously. HEPA Filter: Effective to 99.97 for pollen, drifting dead skin and other lung damaging particles One of the most advanced purifiers on the market today Virtually maintenance free