Like any tool, if misused e-collars can do un-repairable damage. The e-collar is a good training tool if used properly. I find the e-collar very useful when patterning spaniels or recalling fast moving pointers. Bark collars are also valuable for keeping your dog (and your neighbors) quiet. and calm. New technology allows for kinder stimulus reinforcement . Very non confrontational to your dog
You should always get the proper training instruction before using them.