The ARC USB connects to the computer via USB and communicates directly with TotalMix FX. It features 15 freely assignable, illuminated buttons, an encoder knob, and a jack socket for connecting a footswitch. The ARC USB is a USB 1.1 MIDI remote control for the Fireface UFX+ and all other RME devices. Since it operates as a UAC 1 class device, it is natively compatible with Windows and Mac OS X. Once registered in the operating system, the ARC USB is automatically recognized by TotalMix FX, and communication for controlling the UFX+ occurs through simple MIDI commands.