I have one and I think it's great. Blaze, now 15 months, used to bolt out the front door. I have 3 boys age 5 to 10 and it was difficult to prevent this. Became a problem once he was able to jump the raised baby gate between the kitchen and front hall. So I got one and it was great but he chewed through the collar when one of the boys took it off and left it on the floor . I took a while before I replaced it and he forgot the boundary and one day this past Spring he got hit in an instant by a neighbour's car. It was bad but he made a full recovery thank God. Anyway I replaced it and the key is to keep the collar on from dawn til dusk because I certainly could not police the door all the time. It is not uncomfortable. I tested the level on myself so I know it's a frightening buzz but does not hurt. Anyway the back fence would not prevent another bolt out the front door so I'll be keeping it for a while. Gives me peace of mind. Took less time to train than I would have thought. I've nothing negative to say about it. I know it may not be 100 % effective in some cases and for all dogs but it reduces the risk of an unexpected bolt I think . I'll be interested to read what other opinions are out there.
Carolyn
Carolyn