About a year ago started to use the bar, but before it our Deben location system was enough for us. When we found the dog under us, just put the box to the ground, give them more 5 minutes, and if they were still there, we started to dig them out.
A year ago we experienced the mentioned situation when the box displayed 0,3 everywhere, and then the bar was very very useful for us.
The best thing is to put both of them to the backpack.