From the manufacturer:
Casio's CTK-720 61-key portable keyboard was designed for beginners and intermediate musicians. It features include 61 full-size keys, 32-note polyphony (the number of notes that can be played simultaneously), 242 tones, 100 rhythms, 100 songs, LCD display, dual speakers, transpose and tuning function, general MIDI (GM makes it possible to communicate with other MIDI devices regardless of the brand.), USB port, microphone input and volume for singing along. The CTK-720 keyboard also includes the Casio 3-step lesson system.