Material: made of electronic components, internal conductor: pure copper. Features: The module uses thyristors, with a withstand voltage of up to 1200V. The regulator has a peak voltage absorption circuit, which can effectively protect high-power thyristors, has a long service life and is more durable. High-quality CBB capacitors can withstand 630V DC withstand voltage. Note: The module is connected to an AC voltage of 220V, so safety must be paid attention to during the debugging process to prevent electric shock accidents. Specification size: high temperature resistant FR-4 circuit board circuit board 35MM * 48MM, external size: 48MM * 60MM (knob direction) * 26MM (height) Package contains: 5 * 50-220V 25A AC motor speed regulator