1. No DC isolated supply: suitable for lithium battery supply, used to modify Bluetooth headset 2. DC isolated supply: suitable for retrofitting speakers, amplifiers, car to increase the Bluetooth function, perfect solution to the common current sound, noise 3.Two mobile phones can be connected at the time (: 2 mobile phones are paired last automatically) 4.With call, Qualcomm, Bluetooth V5.0, , on, the default volume is the largest 5.Using the amp chip, the sound quality is better GND and BAT: 3.7V lithium battery (3.3V-4.2V) GND and VCC: Select 5V or 12V supply according to DC isolation module L, G, R are single-ended outputs, can be connected to headphones, amplifiers, audio and other input devices M+ and M- are the positive and negative poles of the microphone is the common end of the button, and the other end of the button is connected to VOL+, VOL-, PREV, , PLY Material: PC+Metal colour: green Package Contents: 1 x Bluetooth 5.0 receiver board( No DC isolation) Only the above package content, other products are not included. Note: Light 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.