The SportDOG Brand SDF-100C In-Ground Fence System features a smaller and sleeker Collar Receiver than the original In-Ground Fence system (SDF-100A). The collar features a Li-Ion battery that charges in two hours and has a one to two-month battery life. Now featuring seven levels of static stimulation as well as vibration and tone, it's easier than ever to keep your dog safe and secure. With 1,000 feet of wire and 100 flags, you can contain an area as large as 1 1/3 acres. Multiple dogs? Additional collars are available for purchase.