Therapeutic Function Holding this little music box, winding it, watching the little gears moves, and listening to the music, which in itself is soothing to the ears none Batteries Required The sound power from spring, use the to turn the spring 3-4 circles, then release and will be playing Full playing time ( twist to the end) will be 3-4 minutes none Hand Crank This is a windup music box, not like hand crank music box, you need to shake the handle all the time you are tired with hand crank music box, then this windup music box can surprise you and make you relaxed Wonderful gift, sweet warm friend family and yourself Materials, make from materials