Interface details: USB powered Universal Micro-USB 5V power supply 3.7-5V Supply Pad External 3.7-5V lithium battery power conversion LED indicator Bluetooth mode long blue light 3.5mm stereo audio interface Standard 3.5mm interface, output stereo , plug in headphones, connect amplifiers and other devices Instructions: After the power is turned on, the blue indicator lights up and enters the Bluetooth mode; the English "The bluetooth device is ready to pair" is displayed, indicating that the Bluetooth mode is entered and waiting for pairing; the "VHM-314" searched by the mobile phone Bluetooth is the device name of the decoding board. Click on the connection, the decoder board prompts "The bluetooth device is connected successfully", indicating that the decoder board and the mobile phone are connected successfully, you can . color:Black Material:ABS Package Contents: 2 x MP3 Bluetooth 5.0 decoder board(Without battery) 2 x case 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. :90dB; +N:-70dB; Crosstalk:-86dB; DNR:91dB LOS: 15m; Plate size: 38 x 36mm; Shell size: 42.85 x 39.8 x 16.76mm Support Profile:A2DP/AVCTP/AVDTP/AVRCP/HFP Specifications: BT5.0 Power Supply:3.7-5V