MIDI INSTRUMENT CONTROLLER Korg microKEY Air-25 controller keyboard. 25-key Natural Touch mini-keyboard. Controllers: Joystick, Arpeggiator button, Sustained / TAP button, Octave buttons. Change of Eighth -4 - +4. USB Type B connections (x1). Bluetooth Low Energy wireless protocol (complies with the Apple Bluetooth Low Energy MIDI specification). Power: Two AA batteries (when connected wirelessly, use alkaline or nickel-metal hydride batteries). USB bus power (when connected via USB).