The Roland WM-1D is a USB dongle that lets your Mac or Windows computer send and receive MIDI information wirelessly at a range of up to 30' from a WM-1 unit (available separately). In addition to MIDI note data, you can send MIDI sync for tempo, effects, LFOs, loops, and more—all without connecting a single cable.
The WM-1D plugs into an available USB-A port on your computer and is used in conjunction with a WM-1 adapter connected to the 5-pin DIN MIDI ports on your keyboard, controller, or drum machine. In Standard mode, you can connect up to 4 devices, but the latency will range from 7.5 to 15 ms, which may create timing issues. For a more responsive playing feel, use the Fast mode to lower the latency to 3 ms—just know that when you select Fast mode, you can only connect to two devices (instead of three in Standard mode).