Specification:  Product name: AC 220V 4000W Variable Voltage Regulator.  Material: Metal shell.  Size: 11.5*10*6cm/ 4.5*3.9*2.4inch(Approx.).  Weight: Approx.500g.  Input Voltage: AC 220V.  Output Voltage: 0~220V (Adjustable).  Adjustable Voltage Range: 0~220V.  Max Power: 4000W.  Rated Current: 9A.  Max. Current: 18A.     Features:  Core chip adopts high power thyristor.  With adjustable knob for stepless voltage regulation.  No delay, anti-surge, anti-spike, RC absorption multiple protection.  With universal power socket and power supply light.  With heat dissipation port for fast heat dissipation.  4000W High-power Motor Fan Variable Thyristor Electronic Voltage Regulator Controller.  Adopts metal shell structure, high temperature resistance, flame retardant, not easy to rust.     Tips:  Precautions and instructions for use:  1. When measuring the output voltage when it is empty, it is a virtual voltage. It must be connected to a load of 20W or more to measure the correct output voltage.  2. Input AC power, the output is also AC, not DC.  3. The above mentioned 4000W refers to the ultimate power when working under resistive load.  The inductive load is 1/3 of the resistive load. The resistive load means that the inductive load such as a tungsten filament lamp or a heating wire is a series-excited motor, etc., and the circuit board electronic products are used with caution.  4. This product is a metal case and must be grounded safely.     Package included:  1*Voltage Regulator