This exterior wall cap accessory was designed for use with WhisperComfort™ and Intelli-Balanace™ 100 ERV. It conveniently allows both exhaust and supply airflow through a hole in the building envelope. FV-WC04VE1 is ideal for use in smaller, multi-family applications. It is not recommended for use at cfm settings higher than 50 cfm. Panasonic WhisperComfort™ Exterior Wall Cap, For Use With: WhisperComfort™ FV-04VE1 and Intelli-Balanace™ 100 Energy Recovery Ventilator, Specifications: 0.8 Sone, ABS/Galvanized Steel/Polypropylene