Broan ZB80M Ultra Series Multi-Speed Motion Sensing Ventilation Fan, 80 CFM, 6" or 4" 80 CFM quickly reduces humidity to prevent or eliminate fogged mirrors and manage moisture in bathrooms up to 70 square feet Ultra sense m, motion sensing technology, offers a hands-free solution for maximum convenience Multi-speed operation handles demanding spot ventilation needs, but can also pull double-duty as a great continuous ventilation solution to meet today's stringent requirements Ultra silent with qstream 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