The board uses six disassemble amplifier tubes, 4 responsible for the left and right channels, the other two connected to BTL circuit for subwoofer , wiring is very simple, especially for DIY. Working voltage: AC double 18-24V 100W transformer output : 3*80W Max subwoofer output: 120W Max Left and right channel output: 100W+100W Load impedance: 8ohm Frequency response: 20Hz-30KHz Distortion: 1% size:15.8x16.7x4.2cm Material:ABS colour:Photo Color Package Contents: 1 * Audio Amplifier Board Only the above package content, other products are not included. Note: Light reflection and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.