Smart Register Booster Fan for 4″ x 10″ Vent Holes – 10-Speed Quiet Vent Booster
This booster fan increases airflow to distant rooms to balance temperatures. Plus, a built-in aromatherapy chamber lets you scent your space while cooling or heating. Just add your favorite essential oil to enjoy a fresher room atmosphere while the fan runs, combining stronger airflow with a light, pleasant fragrance.