Professional dog walker, every day I take 6-12 dogs to the woods and let them walk off leash for hours. I have 6 of these collars (some T5, some TT15). I put collars on dogs that hunt deer so if we startle the deer and it starts chasing, I can follow and eventually catch the pack. With the long antennas on the collars and the Alpha tracker, I can locate dogs up to 1/2 mile away in hilly, densely wooded areas. Shoot further than that crap for consistent tracking, but as long as I keep moving towards the last known good GPS position I can pick up the signal again. The battery life is amazing and lasts for days on collars. The problem with these collars is that they ALWAYS break. There is an almost 100% chance that the GPS device will fail within the first 6 months and the collar will become unusable. I'm not talking about breakage due to physical damage or rough handling or whatever. you just. stop working one day. Good luck if your dog is chasing a deer within 3/4 mile of you when this happens. The silver lining to this dark cloud is that Garmin's product support is very friendly and efficient, guaranteeing that new collars will not raise any questions if you've had them for less than a year. While they have major reliability issues, this is by far the best dog tracking option I've found and I've tried many of them. They're way better (and way more expensive) than mobile trackers like the Whistle. I would recommend them with the big caveat that they are not designed to last forever.
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