Easy Installation: Hang on baby crib holder in seconds No Batteries Required: Spring-driven music box plays sweet melodies with a simple rotary switch Customizable: Hang small plush dolls on the bottom hook for added fun Soothing Sleep: Lullaby melodies help your baby fall asleep peacefully Musical Cognition: Enhance your baby's cognitive development with the power of music. This music box is designed to hang on baby crib holder, easy to install Spring-driven music box doesn't need extra battery, just rotate the rotary switch and then listen to sweet melody. You can hang small plush dolls on the bottom hook.You baby will fall into sleep along with soft and beautiful melody.Help to pacify crying baby and enhance your baby's cognition of music