I was a beta tester (well, more specifically my dog was!) for the Fi collar. It's pretty amazing tech with clever power-saving features. We tested it for ~2 months without having to re-charge.
Hi HN!<p>I'm a backend engineer at Fi and we just launched our GPS dog collar and activity tracker powered by the low power LTE CAT M1 network and Bluetooth Low Energy.<p>Happy to answer any questions!