QCC3031 supports , AAC, , APTXLL, APTXHD With call function, low power consumption, power on, the default volume is maximum, support pairing. 3.6-5.5V power supply (compatible with lithium battery power supply or 5V power supply) VCC and GND are the power supply pins, L, G, R are connected to earphones M+ and M- are the positive and negative 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 Key Description: "VOL+": Short to increase the volume, long to increase the volume "VOL-": Short to decrease the volume, long to decrease the volume continuously "NEXT": short a song "PREV": Short the previous song "PLY": Short to play/pause/answer/hang up, long for 1 second to reject the call Special function description: "PLY": Long for 3 seconds to force enter pairing mode, long for 6 seconds to clear the pairing list "PLY" + "VOL+": and hold for 1 second to enter the search mode "PLY" + "VOL-": and hold for 1 second at the same time to enter the searched mode "VOL+" + "VOL-": and hold for 1 second to disconnect Colour:As Shown Material:PC Power amplifier board size: 5.7 x 3.3CM Package Contents: 1 Amplifier Module 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.