Add an unlimited number of pets to your YardMax‚Ñ¢ In-Ground Fence‚Ñ¢ system with this extra Receiver Collar. YardMax‚Ñ¢ maximizes the amount of yard space for your pet to play freely in. When your pet nears the boundary, the collar will give a warning beep, followed by a static correction to remind your pet to stay within the boundaries. Your pet will be enjoying greater yard freedom in no time!