The Casio CTK-900 61-Key Portable Keyboard gives you 61 touch-sensitive keys, 824 pristine ZPI tones, 32-note polyphony, and 176 rhythms, so that your palette for creating music is virtually without limits. IDES software lets you access even more tones, DSP settings, songs, rhythms and more via Casio's website. 242 DSP effects including 16 reverb and 16 chorus, synthesizer function, MIDI I/O, tune and transpose function, backlit LCD, and 4MB Flash ROM make the Casio CTK-900 keyboard an amazing value for its price! The Casio CTK-900 is powered by 6 "D" size batteries (not included) or optional AD-5 AC power supply (see item # 338700).