The M-Audio Keystation 61es is a high quality 61 note Semi-Weighted USB MIDI Controller Keyboard. The M-Audio KEYSTATION 61 ES (61ES) works on either MAC or PC and is BUS powered, meaning it's powered via the computer so there's no need for a bulky PSU. The M-Audio Keystation 61ES is designed to easily integrate in any computer music environment. More advanced users can control software synths, external sound devices, and more with the assignable slider, and pitch and mod wheels. The M-Audio Keystation 61 ES includes Ableton Live 5 lite within its M-Audio software bundle.