This product uses a IC chip with overvoltage protection, overcurrent protection, overheating protection and short circuit protection. The input voltage is 12-24V, the output power is 50Wx2 (the output power is 50Wx2 when the input voltage is 24V, and the output power is 25Wx2 when the input voltage is 12V). The volume can be adjusted by turning the knob to the right. Turn the knob to the right to increase the volume. Turn the knob to the left. The volume is reduced until the amplifier board is turned off. HD Bluetooth 5.0 or AUX port audio input, two-channel output. Product name: Digital Bluetooth amplifier board Power input: 12-24V Audio input: AUX/Bluetooth Output power: 50Wx2 (power supply 24V=50W, power supply 12V=25W) Impedance matching: 4-8Ω Number of channels: two channels Color: As Shown Material: plastic Package Contents: 1 x Digital Audio Power Amplifier Module Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.