Product information: Bluetooth 5.0, supports serial port renaming, supports one-key TWS pairing, supports AUX insertion into TWS pair box, power on and start up, the default volume is the highest. When 16V4A, the maximum output power is 30W; When 12V4A, the maximum output power is 20W. 8-22V power supply, with reverse connection protection, support notebook power adapter power supply. Boards and devices are well-crafted, with sufficient materials and reliable quality. M+ and M- are the positive and negative of the microphone. TX, RX, GND: TTL serial port configuration 9600, N, 8, 1 Power amplifier board size: 7.1x4.3CM Fixing hole distance: 6.6x3.8CM Type: A: Supports calls / B: not supports calls. type: Amplifier Board color:Black Material:PCB+electronic components Package Contents: 1 x TWS Amplifier 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.