HQRP 3-Pack Filter Bionaire Humidifier BCM655, BCM657, BCM658, BCM658C, BCM658SC Coaster HQRP&reg; 3-pack Humidifier Wick Filter (Type E) Replacement + HQRP&reg; Coaster; Improves efficiency of the humidifier; Traps mineral deposits from the water; Replace filter every 4-6 weeks, depending on usage and hardness of water. 2 weeks DOA replacement warranty!