Electronic Dog Fence System - An invisible dog fence which enables you to keep one or more dogs safe in complete freedom within a perimeter that YOU define without the need of an ugly containment fence, - You will be able to rest assured that an unlimited number of receiver collars can be used within one perimeter to contain as many dogs as you wish safely in the same area, The EF-4000 advanced technology makes it adaptable to any type of terrain: open, wooded, hilly, fenced, unfenced, hot or cold! How does it work? A discrete, state of the art perimeter wire (up to 450 yard) is easily placed under the ground or raised on an existing fence, This wire carries a signal from our small, mountable transmitting device, Your dog wears our adjustable, hi tech receiving collar that communicates with the perimeter wire, When your dog first approaches the wire he will enter a buffer area which we call the ""warning zone"" (which is set by you on the control panel), Your dog is then alerted to the fact by a beep from the collar, via our top of the line internal speaker, As your dog gets closer to the wire within the warning zone, he will enter a correction zone, Once entering this zone, he will be corrected by a small, safe, and most importantly HUMANE electronic stimulus, As your dogs leaves the designated correction zone the impulses from the collar stop, SKU: DLRDY089553