The eco-friendly ChargePAK D1 allows for portable listening when used with the Pure Pop Mini, Pop Midi, Pop Midi with Bluetooth and Pop Maxi. Much more economical to run than regular batteries, the ChargePAK D1 is also significantly kinder to the environment because it ultimately reduces the amount of batteries which end up in landfill sites. And no separate charging unit is required either because the D1 charges inside of the radio. Easy to install and use, the battery can provide up to 18 hours of wireless listening for selected Pure Pop radios .