Post-filter kit for 16X25-inch F300 and F50 electronic air cleaners. This item is sold in a pack of 2. Filter measures 16 x 12.5-inch. May be vacuumed clean but not washed. Honeywell maintains filter will last 6 months. Improves filtration efficiency of Honeywell F300 F50F F58F electronic air cleaners. Contains antimicrobial coating to protect against growth of bacteria and fungus.