The Fi collar uses LTE-M, a brand new cellular network technology that dramatically improves battery life and allows you to accurately determine your dog's location - with weeks (up to 3 months!) of battery life under normal usage conditions as compared to a few days (1 week maximum!) for other smart collars.
The Fi collar's integrated design is sleek and low profile, as well as lightweight. To see a comparison of Fi against other smart collars, feel free to visit this help article: Fi Collar vs. 3G Trackers.