JBL BATTERY 600 Rechargeable Battery For PartyBox 520 And Boombox 4Even the best parties have to end sometime, but your JBL speaker can keep the vibe going twice as long with JBL Battery 600. When your rechargeable battery is running out of juice, it takes just seconds to pop a fresh battery into the slot on the back panel. Meanwhile, the battery can recharge in the charging case. You can also use the case as a powerbank to charge your tablet, laptop or smartphone* with the convenient USB C port. Double the great