HQRP 3-Pack Wick Filter for Sunbeam Humidifier HWF100, SF235 Replacement 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!