To play music on the OpenSwim Pro, you can transfer MP3 files directly to the device. To do this, connect the headphones to your computer using the 4-pin magnetic cable supplied. Then open the virtual drive "SWIM PRO" on your computer and drag the desired music files into it. Supported formats are MP3, FLAC, WMA, WAV, AAC, M4A and APE. Alternatively, you can also use Bluetooth to stream music from a connected device.