Hydrofarm's Fan Speed Adjuster was designed especially for centrifugal fans. This means it will help prevent damage to fan motors, ensuring longer life. (Meant for use with brushless motors, and all Hydrofarm inline fans, not 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. Features Internal electronic auto-resetting circuit breaker State-of-the-art electronics throughout Rated for 350 Watts Max 120VAC voltage capacity Hydrofarm Brand “Other” Brands Specifically made for use with centrifugal fans. Correctly manipulates input power sine wave for type of motors being controlled. Made for routers (different style of motor). Incorrect clipping of input power sine wave leads to shorter fan life and excessive noise. Higher sensitivity control allows precise flow adjustments. Low resolution voltage control doesn’t allow for proper adjustment of flow. Stall speed range eliminated to eliminate fan stoppage. Allows fan to stall if fan speed falls. Internal self-resetting circuit breaker in case of over-voltage. Must manually replace fuse and/or reset breaker switch, possibly leading to a scenario where your fan isn’t running for an extended period of time. NOTE: Use only with ball-bearing inline/centrifugal fans. Not recommended for use with "squirrel cage" type fans or the 12" Max Fan. For the 12" Max Fan, use speed controller CFH0350290.