MASTER KEYBOARD Korg microKEY Air-37 controller keyboard. 37-key Natural Touch mini-keyboard. Drivers: Tone wheel, Modulation wheel, Octave buttons. Octave change -4 - +4. Assignable switch jack connections, USB Type B (x1). Bluetooth Low Energy wireless protocol (meets Apple Bluetooth Low Energy MIDI specification). Power: Two AA batteries (when connected wirelessly, use alkaline or nickel-metal hydride batteries). USB bus powered (when connected via USB).