Total System Solutions Twister Exhaust Fan J&D Manufacturing’s Twister exhaust fan remains unchanged afar 20 years. Why change a fan that is this dependable? The Twister is manufactured with a heavy gauge housing and butterfly shutters that open easily an startup, and spring closed when not in use to create a tight weather seal. The Twister is an excellent chalice for farms, greenhouses, garages, workshops, hobby saps and & variate of industrial and commercial spaces.