The PetSafe In-Ground Fence has been proven safe, comfortable, and effective for all pets up to 55 pounds with neck sizes 6″” – 26″”. Complete system for up to 1/3 acre. The system works by producing a radio signal from the Fence Transmitter through up to 4,000 feet of Boundary Wire. The boundary wire is buried or attached to a fixed object to enclose the Pet Area. You temporarily define the pet area with boundary flags for a visual aid in training your pet. Your pet wears a Receiver Collar with contact points that touch his neck, and, once trained, is allowed to roam freely in the Pet Area. When your pet reaches a warning zone, the receiver collar gives a warning beep. If your pet continues into the static correction zone, a safe correction will be delivered through the contact points until he returns to the pet area.Features:Small waterproof Receiver CollarQuickFit buckle provides quick release and perfect fit every timeCovers up to 25 acres with additional wire and flagsFlexible collarReceiver correction 4 levels plus tone onlyLow battery indicatorBuilt-in lightening protectionOperating and training guideStep-by-step installation and training DVDLifetime limited warrantyGeneral Info:Will transmit up to 25 acres or 4000 feet of wireBoundary Control Switch Settings: A = Greater than 2,400, B= up to 1,300, C= 1,300-2,400 feetShould be installed in a dry and protected environmentBoundary wire must be copper and insulated20 gauge wire recommendedBoundary Width is 20% Warning Zone and 80% Static Correction ZoneTransmitter Specs:Height: 5.75″”Width: 4.75″”Depth: 2.10″”Frequency: 10.65 kHz StandardFlip Open Front CoverMedium Gray with Dark Grey TrimTwo green indicator lights (loop and power)Ground T