Broan XN110H Ultra Green Single-Speed Humidity Sensing Fan (110 CFM, 0.3 Sones) 110 CFM very quickly reduces humidity to prevent or eliminate fogged mirrors and manage moisture in bathrooms up to 100 square feet, so your vision will always be clear and your surroundings will always be comfortable ULTRA Sense H, Humidity Sensing Technology, means no longer needing to remember to turn the fan on when you shower ULTRA Silent Sound Technology results in operation at less than 0.3 Sones - the quietest sound rating attainable - for an environment that is so quiet, you'll likely forget the fan is on ULTRA Quick Installation Technology uses an exclusive telescoping mounting frame with pre-installed screws, snap-in housing, snap-in blower and an inside-out mounting duct connector Retrofit installations can be done entirely from the room-side - no attic access required. This means a faster, easier installation, so you can move on to something else