No DC isolated supply: suitable for lithium battery supply, used to modify bluetooth headset With call, CSRA64215 low consumption, on, the default volume is maximum Using the amp chip, the sound quality is better. GND and BAT: 3.7V lithium battery supply (3.3V-4.2V) L, G, R are single-ended outputs, which can be connected to input devices such as headphones, amplifiers, and audio M+ and M- are the positive and negative poles of the microphone head Color: green Material: PCB is the common terminal of the button, the other end of the button is connected to VOL+, VOL-, PREV, , PLY respectively, and the length of the button line is within 5cm 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 "": short press the song "PREV": short press the previous song "PLY": short press to play/pause/answer/ 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 "PLY"+"VOL+": Press and hold for 1 second at the time to enter the search TWS mode "PLY"+"VOL-": Press and hold for 1 second at the time to enter the searched TWS mode "VOL+"+"VOL-": Press and hold for 1 second at the time to disconnect TWS Package Contents: 1 x Bluetooth Receiver Board Only the above package content, other products are not included. Note: Light reflection and different displays may the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.