The bidirectional high-power thyristor is used, because the current can reach 40 amps, which solves the over-current problem caused by the resistance of the electric furnace wire being too small under cooling. 0-100% (220 volts, 100-level adjustment, non-linear) can be adjusted arbitrarily for electrical appliances. Such as: electric furnace, water heater, dimming of lamps, small motor speed, electric iron temperature. So as to achieve the effects of dimming, temperature and pressure. Available for large appliances with an electric power of less than 2000 watts. Because the power is already large, ordinary household appliances or small factories are sufficient. (This voltage regulator is equipped with bidirectional high-power thyristor, which can be used without adding any components, which is very convenient and practical). Comes with a heat sink. Voltage: AC 220V Maximum Power: 4000W resistive load limit power, it is recommended to use within 2000W for a long time at room temperature Voltage Adjustment: 0-100% (220 volts divided into 100 levels, non-linear) Material: PCB+Metal+Electronic accessories colour: As shown Package Contents: 2 x 4000W SCR Voltage Regulator 2 x Switch Panel 2 x Cable