The Panasonic FV-04WS2 20 CFM bathroom fan comes from the WhisperSupply Wall line. This collection of bathroom fans was designed with the intent to provide residential contractors, builders and professionals with ASHRAE-compliant make-up/supply air fans. This WhisperSupply Wall fan uses a MERV 8 filter to supply fresh air that meets these regulations. This Panasonic bathroom fan is wall-mounted and easy to install. It protects against unwanted draft through in internal interior deflector. This model is compatible with 6" duct installations.