With DC isolation power supply: suitable for refitting speakers, power amplifiers, and vehicles to add Bluetooth-Compatible function to solve common ground current sound and noise; With call, Qualcomm Bluetooth V5.0, , APTXLL, power on, the default volume is the largest. Using TI amp TPA6132, the sound quality is better. L, G, R are single-ended output, which can be connected to input devices such as earphones, power amplifiers, audio, etc. M+ and M- are the positive and negative poles of the microphone.COM is the common end of the button, the other end of the button is connected to VOL+, VOL-, PREV, NEXT, PLY, and the button line is within 5cm. Key "VOL+": Short press to increase the volume, long press to increase the volume "VOL-": Short press to decrease the volume, long press to decrease the volume continuously "NEXT": Short press a song "PREV": Short press the previous song "PLY": Short press to play/pause/answer/hang up, long press for 1 second to reject the call Special function "PLY": Long press for 3 seconds to force enter pairing mode, long press for 6 seconds to clear the pairing list Style:C No DC isolated lithium power supply Colour:Green Material:PCB+Plastic+Metal Size:3.6 x 3.3CM Package Contents: 1 * QCC3005 Bluetooth Audio Module 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.