Wagr Tracker comes with a micro-USB charging cable in the box. Attach the USB end of the cable into any safe, compatible, USB port, and the microUSB into the Wagr Tracker device after removing it from the collar. The LED light will turn orange to indicate that it is charging, and will turn green once fully charged. Your app will also receive a notification once the Wagr tracker is at full charge (takes roughly 2 hours). You can then remove it from charging and reattach it to your dog's collar.