Rechargeable 4400mAh battery pack designed for the Grace Digital Mondo or Mondo Play up to 13 hours of music per charge. Your actual battery life will vary depending on audio volume, distance from your Wi-Fi router, and backlight brightness setting. Provides true portability for your Grace Mondo Wi-Fi radio. Listen to your music anywhere you have Wi-Fi. Your Mondo or Mondo already allows you to enjoy your music wirelessly in any room of your home. Expand your enjoyment of your Grace Digital Mondo or Mondo Wi-Fi radios with the rechargeable battery pact. Add a Grace Lithium Ion Rechargeable battery pack and you can unplug your radio to move it anywhere inside or outside your home with uninterrupted music. You can listen for up to 13 hours between charges. The radio will automatically charge the battery when plugged into an AC wall outlet, even while playing music.