We bought this product as our dog was a wanderer...any chance she could get to go walk-about she went.
Overall, it works well. However when the batteries die, there's a flashing red light on the collar that flashes, but only for a couple of hours. If we didn't notice it, our dog would figure it out after a couple of days, and bolt.
Unfortunately, one night, she got away and was killed on the road.
We don't hold the device responsible. It works well, when the batteries are working. We should have noticed the flashing lights.
However, a recommendation to others, change the batteries on a monthly basis. Make a note...every 1st of the month...The cost of the batteries is nothing compared to the heartache of losing a wonderful friend.