The PetSafe In-Ground Fence consists of a receiver device with adjustable nylon collar, 150m of in-ground wire, and 50 boundary flags. Also known as invisible pet fencing, it allows your dog to have free movement and access within an established defined area. This can prevent your dogs from straying from your property. The dog will receive a burst of electrical stimulation when he or she attempts to cross the boundary. Suitable for dogs over 3.6kg with a collar size of up to 71cm.