eufy Rechargeable Battery Pack with USB-C

Long-Lasting Backup Power: 6,500 mAh capacity, up to 6 months of use from a single charge. Easy to Install and Remove: Intuitive clasp is designed to be simple and quick to use. Charge with USB-C: Power it up with the same cable you use for other devices. Official Accessory: Works with eufy Video Doorbell C31, C30, and E340.