The Roland WM-1D is a USB dongle that provides communication between PC or laptop without internal Bluetooth functionality and MIDI equipment with Bluetooth connectivity. The dongle communicates with the WM-1, which connects between MIDI equipment itself and the WM-1D, and other instruments that connect to the computer via Bluetooth alone. Due to sophisticated algorithms, a super-fast latency of only 3 ms is guaranteed in Fast mode, for time-critical applications such as synchronizing instruments with sequencers this mode is preferred. In addition, the Bluetooth standard used is sufficient for use on stages and in larger studios. If you have to deal with long MIDI cable distances or want to integrate the electric piano at the other end of the room or even use a MIDI Bluetooth controller, the Roland WM-1D is the right helper. The graphic illustrates very well how WM-1 and WM-1D can be used.
For a bidirectional connection between MIDI devices and PC/laptop via Bluetooth, one WM-1 per MIDI instrument is additionally required. If the connection between a MIDI controller and a Bluetooth device (e.g. Bluetooth MIDI controller) is intended, only one WM-1D is sufficient.