The Quick-Release Battery Pack allows you to have backup power for select battery powered Ring Doorbells and Cameras. To charge your battery pack, simply connect it to a micro-USB cord and plug it into a power outlet. If the battery pack in compatible Ring Video Doorbell or Securtiy Cam runs out of power, you can remove your batteries by pressing the quick-release tab on the battery pack. Then, simply slide your second battery pack into your device, and you’re good to go. | Ring | | Quick Release Rechargeable Lithium-ion Battery for Select Devices | Black/Silver | Best Buy