Bluetooth MP3 Decoding Board Module with inbuilt SD Card Slot/USB/FM/and Remote ControlBluetooth Stereo Audio Receiver Module, 3V-5V for Amplifiers Sound Recorder and Sound Circuit Electronic Hobby Kit. This is a Bluetooth audio receiver module, transmitting MP3 and other common audio formats' audio signals. It's simple to set up and use, and once connected to another Bluetooth system such as your phone or laptop, it can receive and translate signals into an output format compatible with speakers. It has three output terminals: L Out, R Out, and GND, to which you can attach a wired earphone through a 3.5mm female jack, or connect its output to the input of a good amplifier device to drive a large speaker.