QCC3031/3034 supports , AAC, , APTXLL, APTXHD AUX audio input, low power consumption, power on, maximum volume by default, 2x4/8 Euro 50W, support external IPEX generation antenna 8-26V power supply (when 24V6A, the maximum output power is 2x50W) VCC, GND: power supply pins, with reverse polarity protection The NE5532 of the front-end TI and the TPA3116 of the latter-stage TI are of workmanship and sufficient materials Key Description: "P/V-": short press the previous song, long press to keep the volume down "+": short press a song, long press to keep volume up "PLY": short press to play/pause/answer/hang up, long press for 1 second to reject incoming calls function description: "PLY": long press for 3 seconds to force into pairing mode, long press for 6 seconds to clear the pairing list "PLY"+"P/V-": Press and hold for 1 second at the same time to enter the search TWS mode "PLY"+"+": Press and hold for 1 second at the same time to enter the searched TWS mode "P/V-"+"+": long press at the same time for 1 second to disconnect TWS Amplifier board size: 8.1 x 5.2CM Material: PCB colour: Green Package Contents: 1 x Amplifier Board Only the above package content, other are not included. Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.