Does anyone know how effective and reliable these collars are in helping to curb a persistent barker!

I know they are reasonably expensive, but it would be worthwhile if I knew that they had quite a good reputation in successful control of excessive barking.

Many thanks for any comments of personal use or knowledge of their use.

The collars do work as does the Master plus, but first we need to know why the dog is barking, can you join and then we will be able to ask the questions that would help us say if the collar would help.