In the 21st century, your phone should last you all day.
With CoBattery, your phone will stay at 100%. Your phone will run off the battery in your case. Once the battery on your case is depleted, your can swap for your fully charged battery.
Heading on a camping trip? Pack both batteries and you should have enough power to last you through the weekend.
CoBattery comes with a case, two batteries, and a charging dock for $79.