Let all of your pets enjoy more outdoor freedom! Add an unlimited number of pets to your YardMax in-ground system with this PetSafe YardMax Rechargeable In-Ground Fence Collar. YardMax 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!