PetSafe Instant Barrier with One Zone. Place this Indoor Barrier near anything you want your pet to avoid. The Indoor Pet Barrier creates a hidden wireless barrier around any area you want your pet to avoid, from the counter or the couch to bins and kids' rooms. When your pet enters the Barrier Area, he’ll hear audible tones from the Receiver Collar followed by a safe, progressive static stimulation. The stimulation is delivered through the Contact Points of the collar that touch his neck. He’ll quickly associate the stimulation with the area you’ve declared off-limits. Add an unlimited number of barriers and collars for multiple pets or to protect multiple areas in your home. Number of Pets: Expandable to any number of pets Automatic Shut Off: Over Stimulation Protection, stimulation stops after 15 seconds Batteries: Transmitter uses 3 x AA batteries (not included), receiver collar uses 2 x 3 Volt lithium batteries (included) Collar Size: Fits neck sizes 15 - 71 cm Expandable System: Add extra barriers for any number of protected areas Waterproof: Lightweight, waterproof receiver collar