This economy make-up air unit is a non-motorized gravity vent. It is an economical choice when a fresh air intake or pressure relief is needed. Can be used anywhere fresh air is needed to replace exhaust air, commercial kitchens, office buildings, bakeries, laundries, factories, warehouses, foundries, locker rooms, etc. Spun aluminum housing for rust free weather resistant durability. Can be roof or wall mounted. Roof curb/ wall mount bracket not included. Made in the USA.