Holmes HM2409-U Digital Cool Mist Humidifier Runs up to 36 hours Humidistat with led display Filter treated with antimicrobial protection and arm and hammer baking soda Uses (1) HWF62 A Replacement Filter 1 year limited warranty Designed for medium rooms Runs up to 36 hours per tank filling Digital humidistat allows you to easily set your desired comfort level with one button, Arm and Hammer embedded for added protection Uses one HWF62 A Replacement Filter 1 year limited warranty