"Keep your dog playing safely within boundaries created by the PetSafe In-Ground Fence free to enjoy the backyard without any worry for you of escape or harm. The system uses four adjustable levels of static correction with automatic safety shut-off that shuts off correction after 30 seconds. Anti-Linger Prevention keeps your pet from staying in the warning zone for long periods of time and draining the battery. Tone-only mode alerts your pet with a beep. Run-through protection increases the correctional level if your dog tries to run through the boundary zone. Waterproof Ultralight receiver collar fits dogs 8 lbs. and larger with neck sizes measuring 6""-28"". Purchase additional receiver collars to add an unlimited amount of dogs to the system. System covers up to 1/3 or an acre with included boundary wire. Add additional insulated copper wire (14-20 gauge) to expand coverage up to 25 acres. System includes receiver collar with RFA-67 battery, transmitter with power adapter and mounting bracket, surge protector, 50 boundary training flags, 500 ft. of 20-gauge boundary wire, wire nuts, gel-filled capsules, test light tool, and operating and training guide."