I have lost dogs for many days (without usage of a gps collar) and am very aware and appreciative of the longer battery life of this new collar to allow for long search times if needed. This system has a mode called “sleep mode” that allows you to put the collar to “sleep” and consume far less battery power. It is meant to be used when you are not actively tracking your dog. When you want to begin tracking your dog again you enter the “awake mode”. The issue that I confirmed with GARMIN helpline is that you must be in RF antenna sight line to wake the collar up. It is not commanded to wake via GPS. If you hunt in hilly country as I do it is likely that the dog will be out of RF range and therefore the collar will be stuck in sleep mode and useless to track your dog. The GARMIN product manual does not make it clear whether this mode is commanded via RF or GPS antenna. If it were via GPS then there would be very little limitation putting the collar into awake mode. As it stands I will not be using “sleep/wake” mode. I want others to know this limitation as well.