The Broan® QTX series very quiet 110 cu-ft/min ceiling humidity sensing bath fan with sensaire technology is an ENERGY STAR certified solution to fight excess humidity and potential mold problems. The fan turns on automatically as it detects rapid increases in moisture at the ceiling level, where steam and humidity rise. After a user defined time period, the fan shuts itself off to save energy and money. The sensitivity is also adjustable. Humidity sensing fans are ideal for high traffic bathrooms, the kid's bathroom or for those who leave the house before humidity is properly vented. The QTXE110S is UL listed for use over a bathtub or shower when connected to a GFCI (Ground Fault Circuit Interrupter) protected branch circuit and fits 2 in x 8 in ceiling construction. Duct with 6 in round ducting. 110 cu-ft/min, effective ventilation to remove moisture and reduce the risk of mold or mildew in most full baths 0.7 sones for ultra quiet performance, you might not notice it's on Sensaire™ humidity sensing technology, senses humidity up to 4X faster than the competition Includes hanger bars on the fan housing for easier installation Energy Star® certified for energy efficiency