When space restrictions prevent use of inline duct fans, EXT External Mount Duct Fans offer through-the-wall solution, and can be sidewall mounted on exterior of building. Units feature external rotor motors, enclosed motor housing for dust and lint, automatic reset thermal overload protection, and built-in backdraft damper. Available in 4, 6, and 8 in. duct sizes, speed-controllable fans provide exhaust and ventilation in tight attic mountings, high rise buildings, and apartments/townhouses.