My neighbor has wireless. It is a transmitter inside the house. You can set the range to have a radius from about 25 ft to 100 ft. If the dog gets within about 5 ft of the radius the colar gives him a warning. When the dog gets to the radius he gets shocked. It works great until the batteries in the colar get old and die.
Problem is UPS delivery men do know about the dog is there and they get bit. Neighbor hood children get in his yard and they get bit. When the dog gets a history of 3 bits police and humane shelter people come and kill the dog. The neighbor keeps buying dogs that bit people he just bought his 3rd dog about a month ago.
I have a wireless too but the radius is set very small. The small dog stays in the house or back yard all the time if he ever escapes from prison the colar shocks the #$%& out of him.