The Indoor Barrier Transmitter sends a spherical radio signal, adjustable to 12 feet in diameter. Your pet wears a Receiver Collar with Contact Points that touch his neck. When your pet enters the Barrier Area, he'll hear a series of beeps from the Receiver Collar, and he will feel a safe, progressive, Static Correction, delivered through the Contact Points on his neck. It is designed to startle, not to punish. The progressive Static Correction will get your pet's attention, but will not cause harm. Your pet will quickly learn to avoid the Barriers that you have set up. Additional Barriers also available.