The KMI MIDI Expander is a small metal-cased unit with jacks for 5-pin MIDI cable "in" and "out" and USB connectors for power from a wall outlet and to connect to the 12 Step, and LEDs that light up when MIDI messages are sent in or out of the unit. The MIDI expander transforms the 12 Step's USB output to MIDI messages that can be sent over 5-pin MIDI connectors. Each of the keys on the 12 Step have bright white backlighting from an LED, so the keys can be seen on a dark stage. As well, each key has a red LED light that turns on if you press the key, to help you know if you are pressing the intended key. The keys have no moving parts; instead, they have sensors embedded into soft, rubbery keys. The keys sense velocity (how hard or soft the foot hits the key), poly aftertouch pressure (whether or not your foot continues to press the key after the initial strike, which can be used to add nuance to sustained notes, such as by triggering vibrato or other effects) and pitch bend (a gliding glissando sound). It weighs 1.0 lb (453 g) and measures 17.5 x 4 x 0.75" (445 x 102 x 19mm). The keyboard can be set to play one note only, or set to a "poly" mode, which can sound multiple notes at the same time. Each preset also has settings for legato, hold, or "toggle", with "toggle" allowing the user to switch between modes. One feature in the 12 Step not found in other MIDI foot controllers is that each key can be programmed to play up to five notes. This way, a violin player performing a pop song as a one man band could program the 12 Step keys to play the chords she needs. For example, the C button could be programmed to play a C major triad chord, the D key could play a d minor triad, the G key could play a G dominant seventh chord, the A key could play an "a minor" seventh chord, and so on. Since the chords are user programmed, the chord voicings for these chords could cover multiple octaves. A bass player in a power trio could program the 12 Step to play power chords, enabling her to provide chordal accompaniment for the lead guitarist's guitar solo with her feet while she plays bass with her hands. The first preset is a chromatic scale starting in C. But even users who only want to play individual notes are not limited to that scale or arrangement.