88-Key Semi-Weighted USB/MIDI Controller Simple Software Control. Start creating and performing music on your Mac or PC with the world's best-selling 88 key keyboard controller: the Keystation 88 MK3. Whether you're a seasoned pro looking for just the right controls or are just getting started with USB MIDI controllers, the Keystation 88 MK3 will meet your needs. It is a simple, powerful MIDI controller designed for sequencing music and playing virtual instruments on your Mac or PC. Keystation 88 MK3 features 88 natural-feeling, full-size velocity-sensitive keys and comprehensive controls that expand the range of playable notes, expressive capabilities, and enhance your recording workflow.