Active Air ACSC Duct Fan Speed Adjuster
Hydro farm's Fan Speed Controller was designed especially for centrifugal fans. This means it will help prevent damage to fan motors, ensuring longer life. (Meant for use with permanent split capacitor type motors, all Hydro farm inline fans and Active Air booster fans.)  It will correctly and precisely adjust the speed of centrifugal fans without causing the motor to hum. These controllers are more sensitive than any on the market and are compact and built to last.  Includes an internal, electronic auto-resetting circuit breaker rated for 15 amps.