This filtered make-up air fan is constructed of a G90 galvanized steel housing with a blower, motor, pulleys and belt. The lid is removable with spring loaded lid latches for ample access to all internal components. This unit has a highly efficient motor with a variable pitch motor pulley, which allows for system balancing and field adjustment. Other standard features are vibration isolation, adjustable drive sheaves, a disconnect switch, and 2'' washable filters.