1.The roll-up piano has 88 simulation keys, 14 demo songs, 128 timbre, ，The instrument has 4 built-in metronome，which will make you feel absolutely the same as real piano. | 2.The 88 key soft keyboard is made of silicon rubber, which will bring soft touch to fingers and rebound quickly after pressing.With micro USB port, support midi out, can play with software on computer (software include) | 3.Built-in 1000mAh Lithium Battery Power supply by universal USB charger (DC5V) and 1000mAh lithium Battery inside (include), Rechargeable everywhere. It lasts about 3-5hour on a full charge, | 4.Interface Line out : lt can be connected to active speakers or audio power amplifiers and headphones,allowing you to fully enjoy the stereo output effects.It supports both three-wire headphones and external speakers.Line in : lt can connect to the external audio sources like MP3 etc.Pedal : Sustain pedal, it can extend the duration of the piano sound ending.Type-C interface : Charging interface.Power Switch Built-in a quality speaker MlC : it can connect to the external condenser microphone. | 5. Dear buyer! Thank you for buying our products.. We check the function of each key before shipment. If you get the product and keys do not work, please be sure to charge the battery（3 hours)before using it. This will bring you a better shopping experience. And wish you all the best.