Amplifier board size: 5.7x3.3CM CSR8675 supports APTX, APTX-LL, ATPX-HD Power on, the default volume is maximum, just listen to music 3.6-5.5V power supply (compatible with lithium battery power supply or 5V power supply) VCC and GND are power supply pins, L, G, R are connected to the earphone DCOM is the common terminal of the indicator light, and the other end of the indicator light is connected to LED0 and LED1 respectively. KCOM is the common terminal of the button, and the other end of the button is connected to VOL+, VOL-, PREV, NEXT, PLY respectively Key Description: "VOL+": short press to increase the volume, long press to continuously increase the volume "VOL-": Short press to decrease the volume, long press to continuously decrease the volume "NEXT": short press the next song "PREV": short press the previous song "PLY": short press to play/pause/answer/hang up, long press for 1 second to reject incoming calls Special function description: "PLY": long press for 3 seconds to force into pairing mode, long press for 6 seconds to clear the pairing list Colour:blue Material:PCB Package Contents: 1 x Decoder Board 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.