I bought 3 units and they all have the same problem: the slightest impact can cause them to lose power and require that the power be switched back on. Specifically, when dropped from a height of less than an inch, they shut off w/o beeping or other notice. While attempting to use them in practice, everyone's unit was always off due to this problem, so I will be returning mine in the hope that they will fix this problem in future units. The problem is that the batteries are on squishy springs, unlike the Motorola Talkabout's taut ones; and the circuit lacks a capacitor or other means of storing milliseconds worth of power. They will probably fix it, so not the date of this review: 12/3/02.Also, I assumed that the units would provide automatic position updates to others in a group, but discovered that it only transmits one's location if one presses TALK. Perhaps this will be fixed by a future software release.