There are 2 identical rechargeable battery packs about the size of a D cell. They are run in parallel, for reason of capacity. You can get by with 1. Each unit contains 5, 1.2v Cd rechargebles of the big button type. I have also run 4-AAA alkalines (total 6v) that I soldered together. But you have to keep making packs that way. Nine volts is too much voltage, and no capacity, and big expense. My remedy works very well. But I advise making up both packs, both for weight and capacity's sake. It's the weight that makes the EL fire smooth, along with the ingenious little pin on the drive gear that pushes the mirror back up after the big whack and bounce. Smooth as a Rollei. (almost).