Affordable and portable, the mophie power boost battery charges your devices without draining your wallet. The compact battery offers 20,800mAh of power for up to 77 additional hours of power*. Charge your phone while out with friends or charge your headphones while at the gym so you can keep the music going. The power boost portable battery goes with you for when you need it most. Plus, every battery is triple tested for peak performance and safety.