Holmes HM630-U Cool Mist Tower Humidifier... With it"s state of the art functionality combined with it"s great design that complements any home, this cool mist tower is ideal for medium rooms. It provides a refreshingly cool, invisible mist, as well as a digital humidistat which offers precise humidity control for your optimal comfort. FEATURES: Designed for medium rooms Runs up to 36 hours per tank filling AccuSet Digital humidistat Contains an Antimicrobial Product Protection and Arm & Hammer treatment to key plastic parts Filtercheck monitor Dishwasher safe base 16 hour timer. ? Uses 2 HWF100 filters (E Filters).