Function description of VHM-314 V.20 version: Compared with the old version, the size is the same, the Bluetooth indicator is blue, and the power indicator is red. VHM-314 V.20 supports Bluetooth 5.0 and lithium battery charging, and adds functions such as keys, dial switches, DIY MUTE interfaces, etc. Product name:MP3 Bluetooth decoder board Product number:VHM-314 V.20 Bluetooth version: 5.0 USB powered:Universal micro-USB 5V power supply Power supply:3.7~5V Signal to noise ratio:90db +N: -70db Crosstalk:-86db DNR:91db Support configuration:A2DP/AVCTP/AVDTP/HFP Service Level: 5 meters VHM-314 V.20 Operating Instructions: Key 1: Short once is song, long is the volume increase (there be a "drip" sound prompt at the maximum volume) Key 2: Short : pause/play Key 3: Short once for the previous song, long to reduce the volume Push : Push up to supply power to the battery port. When there is no battery, micro-type supplies power indirectly Pull down switch: micro-type supplies power directly. If no micro-type supplies power, turn off the power. Be Careful: 1. The dial switch is fragile. Please protect the switch carefully to avoid damage, 2. micro-type indirect power supply may cause noise due to insufficient current supply Colour:black Material:PCB+electronic components Package Contents: 2 x MP3 Bluetooth Decoding Board 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.