SportDOG Brand In-Ground Fence Add-A-Dog Collar - Additional, Replacement, or Extra Containment Collar - Waterproof with Tone/Vibration and Shock This is the Collar Receiver only; Compatible with the SportDOG Brand In-Ground Fence System (SDF-100A) The waterproof Collar Receiver sends a tone and vibration as your dog approaches the boundary, and then moves to one of 4 static correction levels that you select, based on your dogs temperament The SportDOG Brand In-Ground Fence can be expanded to contain an unlimited number of dogs with the purchase of this SDF-R Add-A-Dog Collar. The Collar Receiver fits dogs 10 pounds or larger This collar features a low battery indicator so you know when to change the battery and an Anti-Linger feature to prevent your dog from running the battery down by standing in the warning zone. It takes a standard 9-volt battery that lasts 6-12 months The detailed operating guide and a locally based Customer Care Center, available 6 days a week, provide support when you need it By designing our products in the field, with heat, cold, rain, snow, dust, mud, and wind in mind, SportDOG has become the most recognized brand in the electronic tracking and training categories, making the promise to always create "Gear The Way You'd Design It"