WhisperGreen Select Pick-A-Flow 30 to 110 CFM Bathroom Exhaust Fan Flex-Z Fast Bracket 4 or 6 in. Duct Adapter FV-0511VKS3

The Panasonic WhisperGreen Select FV-0511VKS3 runs quietly at a low continuous speed to keep air fresh, then ramps up to a higher speed when a wall switch or sensor turns it on, returning to low after a time you set, with airflow adjustable from 30 to 110 CFM. Its DC motor is ENERGY STAR certified and rated for airflow at 0.5-in. static pressure, so it keeps moving air even on long or bent duct runs. Three plug-and-play module slots accept Wi-Fi, motion, condensation, and multi-speed modules, and the Flex-Z Fast bracket with a 4- or 6-in. duct adapter lets you install it from below the ceiling.