Holmes HM-5125 Warm Mist Humidifier Your body needs moisture to function properly, but the minute you shut the windows and turn on the heat, humidity drops from an optimal 40-50% as far down as 20% Dry air makes your respiratory system vulnerable to colds and flu Humidifiers are the answer, and Holmes humidifiers feature higher output, longer run times, and easy cleaning and maintenance of heating elements The HM-5125 delivers up to 2.5 gallons of warm, soothing moisture daily Optimized for rooms up to 700 square feet