Smart&Cool keyboards Roll up Electronic Piano Keyboard Soft Roll Up Electronic Flexible Piano Keyboard 61 Keys, Built-in Speaker, Powered with 4x aaa Batteries, Chargeable with A/C Adapter. Compact and light-weight, making it ultra-portable, Fully-adjustable, Offers great sound and quality 61 Standard Keys Full Size Keyboard (C2-C7) 5 Octaves + 1 Key, 128 Tone Repertoire,100 Background Rhythms. 40 Demonstration Songs - for study and appreciation of classical music, MIDI Out - 16 Output Channel Design - You can choose which channel (1 thru 16) that the roll-up piano keyboard can transmit on. Keyboard Size (Open) : 35" x 6.9" x 0.2" (88 x 17.5 x 0.5 cm)