High Quality: Use high power SCR as internal chip. Thickening metal shell, high temperature resistant and durable in use. Performance Perfect performance: stepless voltage adjustment with rotary knob, no hysteresis, no delay, fast response. The AC voltage regulator cover is equipped with a universal multi-purpose socket and current indicator. Effectively protect high power thyristors from overvoltage and voltage limits with multiple protection. Note 1: The above 4000W refers to the maximum power when working under resistive loads. The power at inductive load is 1/3 of the resistive load. The resistive load applies to tungsten lamp, diew, online excitation motor and more. Electronic products with circuit boards should be used with caution. Note 2: The measured output voltage is a virtual voltage when there is no load. It needs to be connected to a load of 20W or more to measure the correct output voltage. The output is an AC metal housing and must be safely earthed.