The potentiometer adjusts the volume with a switch for easy control of the volume, making it Perfect for DIY speakers.If it is a metal box, you need to bring out the Bluetooth antenna. The copper DC connector is used to withstand high current and no heat. Capacitor 470uf35V solid capacitors power storage and heat dissipation, and stable power supply is a prerequisite for good sound quality. Free DC head lead, compatible with the input power interface of this product, even if you don't have a DC head adapter or battery, it can be easily wired. 5.0 Bluetooth version, the transmission efficiency is higher, the transmission distance is farther. Power supply voltage: 5-24V Number of channels: left and right dual channels Bluetooth version: 5.0 Bluetooth transmission distance: 15 meters Protection mechanism: self-recovery overheating protection, self-recovery short-circuit protection. Colour: black Material: plastic Package Contents: 1 x amplifier board Precautions for use: The power switch on the board is the standby switch. After the switch is turned off, the machine is in a low-power standby state. To completely turn off the power or unplug the DC plug on the machine for a long time. Only the above package content, other products are not included. Note: Light 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.