Air Open - Gravity Close. Baked enamel coating on steel frame. Heavy-duty aluminum blades. Bronze bearings. Weather stripping for tight seal.Not recommended for use with LPE and BE series fans. Motor Kit: Used to open WS shutter when shutter is used to provide make-up air (WS shutter should be one size larger than exhaust fan size and should be located on opposite wall for best results), 115V or 230V, 60 Hz 1.