This
review reports:
Garmin is marketing the MIni collars with a 4 mile effective tracking distance compared to 9 miles for the full size TT15 and T5 collar. Initially we expected the new Mini GPS collars to have less tracking distance. However, while testing these collars extensively in the field we can honestly say that we have seen little difference between the new Mini GPS collars and the standard sized TT15 GPS tracking collar when it comes to tracking distance or dependability. At Double U Hunting Supply we have a test track that we run all new GPS collars through for comparison. With the Mini Collars we are seeing a 2.8 miles in hilly, brushy country using a long range antenna on the handheld. We have seen this distance consistently with the full size TT15 collars. We are extremely confident these Mini collars are performing as well as the full size collars regarding the effective distance.
Why does Garmin claim 4 miles? We don't exactly know, perhaps Garmin is changing the way they market the effective distance to a more "expected" distance rather than marketing a "best case" distance. Any hunter who has spent time behind these GPS collars understands 9 miles is not a distance that is easily achieved in the real world. However 4 miles with any of the Garmin tracking systems is more achievable. My professional opinion is that Garmin is hoping their customers will expect a much more "real world" tracking range.
Full review is worth a read.