Yescom 350W Electronic Fan Speed Controller Variable Adjustor for Hydroponics Inline Duct Exhaust Ceiling Fans 3 Modes 3A 350W variable fan speed controller Fuse Protected; Lightweight, practical and easy to use; Safe and environmental friendly Speed control dial to control variable speed (Low/Medium/High) and OFF; With built-in grounded control outlet and US standard plug, plug and play Make your fan quieter when adjusting to low or medium speed; Perfect for controlling speed of high velocity inline fan and mini blower Note: Please only using it with FANS that have a universal brush type motor (Eg: Inductive Fan). Do NOT use on brushless type motors (Eg: Magnetic Induction Fan).