ITEM NAME:3.7V-5V Mini Bluetooth Audio Lossless Decoder MP3 Receiver Amplifier Module W7I4 1.Parameter characteristics Power Supply 3.7-5V SNR 90dB THD+N -70dB Crosstalk -86dB DNR 91dB Support Profile A2DP/AVCTP/AVDTP/AVRCP/HFP LOS >15m 2.Interface details USB.As shown below. 1X 3.7-5V Mini Bluetooth MP3 Decoder Board Power amplifier Board Bluetooth 4.1. 3.5mm stereo audio interface Standard 3.5mm interface, output stereo sound source, plug in headphones, connect amplifiers and other devices.