5-STAGE FILTRATION: The Horizons composite filter combines 4 filtration layers plus an optional ionization feature to create a 5-stage filtration system. Includes pre-filter, particle filter, granulated carbon, and cold catalyst layers with optional on-demand ionization. GRANULATED CARBON LAYER: Granulated carbon is great at reducing odors, harmful gases, VOCs, and decomposing formaldehyde. The unique honeycomb structure is designed for maximum coverage and powerful odor elimination.