With this Battery Replacement Kit, your little one will be able to play music non-stop! Each battery set, including the ones that come in the books, provides 1 hour and 20 minutes worth of songs. That's are a lot of times pushing the button! The Battery Replacement Kit Includes: - 9 Replacement batteries. - Teeny tiny screwdriver made to fit perfectly for our books *These batteries are made only for Musical Books. Cali's Books Timeless Collection uses different batteries (3 AAA )