dog training shock collars

Is there a training shock collar can also have a dog within a certain radius of your body and your device?
This is called a leash. Seriously, why do that? This would make your dog crazy, you never know where the border is not knowing if their next step will be to radiating from it. It's not like you can communicate with your dog, stay within 20 meters from me, or you 'll surprise. "He does not know how to measure it. What you will find a very scared dog. And Krysia, underground fences are very different to have a portable device for determining the radius of shock. A dog can learn from the boundaries of an invisible barrier and prevent a device that is always in motion a border that travels with him – the dog is to guess.
It’s Me or the Dog- Shock Collar