PianoMaestro Learning System - Fits Casio Celvano AP-220 AP220 AP-420 AP620 AP-620 CDP100 CDP-100 As seen on TV, WIRED and Gizmag! Learn to play any piano piece in 30 days, or your money back Adds guide lights to ANY acoustic or digital piano  reads standard piano MIDI files Works with PC and Mac (Mac via download) Slow down playback, practice left and right hands separately, repeat a few notes at a time