I am caring for a friend's stubborn two year old terrier. I was having an awful time keeping him from dashing out the front door. I have a relatively small area where the front door is. I didn't want to mess with the wired fences you bury in the yard and I also didn't want to spend 300.00 for one of the outdoor wireless units. I bought this at lowes, same model number but their documentation claims 20' range. Either way I only need about five feet of range, I am using this with the "stubborn" dog 9v collar as he is 60 pounds. Took about five minutes to plug this in, put it on a nearby shelf and another ten minutes to adjust the range to the collar and the correction level on the collar. The total investment was around 150.00 and does what I need, keep the dog from dashing out the door when I come and go. His first experience rushing the door (apparently full strength zap) was apparently enough to convince him to back off at the first beep when entering the protected zone when I came home. Very happy with this. Design improvements I can suggest are mounting holes on the case for wall mounting and a separate power switch, I also don't like where the AC adapter plugs in, the side or back would be better I think.