Batteries included. This product uses three AG10 button cell batteries. AG10 Button Batteries also known as 389, 390, 189, LR54, GP89A, L1130, LR1130, L1131, RW89, V10GA. Batteries are a necessary part of our books. Quality of the sound is very dependable on batteries condition. Batteries should be changed when sounds mix, distort, or become otherwise unintelligible as batteries weaken.