NEW Waterproof Underground Electric Shock Dog Collar Fence System for 1 Dog

How does it work safely? The pet wears a lightweight collar which emits a warning sound when the pet nears the boundary. If the warning is ignored and the pet crosses beyond the boundary of the fence, the pet receives a mild electric shock from the collar. The stimulus delivered to the pet may be applied more frequently and at greater strength as the animal approaches the boundary. The pet soon learns to avoid the invisible fence location, making it an effective virtual barrier. Animals (including humans) not wearing the collar are unaffected by the defined boundaries. Dogs are smart, they will gradually learn to avoid this correction, and stay where is safe. Package Contents: 1 x Indoor wall-mounted transmitter; 1 x Power plug; 1 x receiver collar; More collars are available if you have 2 or more dogs, there is no limit to the number of dogs. 1 x 9 Volt battery for collar; 1 x boundary wire of 300 meters; 1 x Extra metal contact points; (extra set are longer for long hair dogs) 20 x Training flags; 1 x Test bulb; 4 x screws; 1 x User's manual.