* A duct fan designed to boost airflow in HVAC systems and ventilate homespaces like attics and workshops.* Features a variable fan speed controller, enabling you to optimize airflowand noise level for any application.* Unibody die-cast construction with no welded seams; reduces vibration whileensuring smoother airflow.* AC brushless motor with steel blades and lubricated bearings; not suitablein restricted airflow applications.* Duct size: 4” | Dimensions: 7.28 x 3.95 x 3.95 in. | Airflow: 106 CFM |Noise: 28 dBA | Bearings: Dual Ball