Features Used for motor speed regulation and can adjust the output voltage through the precision multi-ring potentiometer. AC 0V-220V continuously adjustable, 0 lag, 0 delay, ultra-high heat dissipation. Anti - surge, anti - peak, RC absorption multiple protection Connect this device with lamp or home appliance in a series connection, then rotate the knob for dimming, speed, voltage, temperature control. High-quality SCR, and the max current is up to 25A. It solves the overcurrent problem caused by too little resistance of the wire during cooling Specification:  Voltage: AC 220V Maximum power:4000W Voltage regulation: AC 0-220v Circuit board: FR-4 circuit board Max. current:40A Size: 6*4*4.5cm/2.4*1.6*1.8in Weight: Approx.75g/2.6oz Note: load must be applied first to adjust voltage. Use method: The voltage regulator can be used in the circuit in series, and the voltage regulator can be connected to the lamp and electric appliance in series (that is, either the lamp or electric appliance can be disconnected from the fire line or zero line, which can be connected to the terminal of the "product"). Simple and convenient operation. Note: you can't adjust voltage before connecting the load Package list:  1 x Motor Speed Controller Package List