Remove and control condensation while improving air quality. These high-performance exhaust fans are designed for use in horticultural and agricultural applications, as well as factories, warehouses, garages, attics and restaurants. n n• Highly efficient shutter style exhaust fans offer improved cooling and ventilation for superior air circulation. n• Rounded guard design prevents excessive vibration and adds rigidity for quiet operation. n• OSHA-spaced guards feature industrial gray polyester powder coating. n• Heavy-duty aluminum shutters have reinforced corners for increased reliability. n• Weather stripping on louvers provides maximum seal and prevents rattling. n• Sizes 12"-24" are pre-wired with 9' grounded cord. 115V. n• 12"-20" fans have 3 speeds and 24" fans have 2 speeds. Variable speed capable models available in all sizes.