The In-Ground Stubborn Dog Fence is specifically designed for stubborn dogs that continually challenge the containment barrier. The dog receives a warning tone as it approaches the barrier. Once in the barrier, the collar has four levels of progressive correction to stop it from leaving the containment zone. The collar also vibrates with each correction. The Anti-Linger feature ensures that your dog doesn't stay in the correction zone and run down the battery. The collar is waterproof and has a Low Battery Indicator so you know exactly when you need to change its 9-volt batteries. Ideal for larger dogs, this radio fence will ensure safety and freedom for your pooch every time!