Product information: Bluetooth 5.0, supports serial port renaming, supports one-key TWS pairing, supports AUX insertion into TWS pair box, power on and 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, supports notebook power adapter power supply. Boards and devices are well-crafted with sufficient materials and 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: B, does not support calls. Amplifier Board color: Black. Material: PCB + electronic components. Package Contents: 1 x TWS Amplifier Board. Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item to be slightly different from the real thing. The measurement allowed error is +/- 1-3cm.