HKEASY&reg; Shock Vibrate Beep Collar Wired Underground Electronic Pet Fencing System Wireless Dog Fence This hidden HT-023 fencing system is among the most reliable,cost-efficient pet containment systems available today. A buried wire transmits a harmless radio signal. When you dog approaches the boundary ,the signal causes the dog's colllar receiver to deliver a warning beep first. If your dog closer to the boundary,the system will issue a mild shock.If your dog continues further,the system will issue stronger shocks until your dog returns to within the boundary you have set up. Your dog will naturally seek to avoid correction,and is content staying withing established boundaries.