MD-501 49 mini sized keys- purchased from Radio Shack 3 years ago for $69.00 plus tax. Never used. Excellent condition. Connects to other MIDI instruments or a computer. LCD display with finger icons - 5 assignable percussion pads - 8 note polyphonic design - play and hear up to 8 notes at the same time- 30 built-in auto rhythms with fill in option to create nd insert original rhythms - 3 step learning feature- plays 50 tomes or special effects at the touch of a button- Transpose - change the key of the music, even while playing.