This handy ChargePAK B1 rechargeable battery pack works with compatible Pure radios, giving you true ‘fit and forget’ portability. It sits inside the battery compartment, and charges up while your radio is plugged into its DC adaptor. The moment you detach from the mains, the ChargePAK B1 takes over, giving you the freedom to listen anywhere. And when you plug back in again, the high capacity Lithium-ion polymer (LiPo) battery begins to charge up again. It really is that simple.