PetSafe Wireless Dog Fence: Select Size and Number of Dogs INCLUDES EVERYTHING YOU NEED: This wireless pet fence comes complete with 1 PetSafe wireless dog fence collar for medium dogs, 1 PetSafe PIF-300 wireless dog fence transmitter, one RFA-67 battery for each collar plus 4 additional batteries, 50 boundary flags, a power adapter, a test light tool and a setup and training manual. CONTAINS UP TO 1/2 OF AN ACRE: The adjustable boundary of the PetSafe PIF-300 Wireless Dog Fence System is able to contain a maximum circular area of 180 ft. in diameter, or 1/2 of an acre. DESIGNED FOR MEDIUM TO LARGE DOGS: The wireless dog fence collar that comes with this system is for dogs weighing 8 pounds and up, with a neck size of between 6 and 28 inches. REPLACEABLE BATTERIES: These wireless dog fence collars run on PetSafe RFA-67 proprietary batteries. Each waterproof collar comes with 1 battery, and this kit includes 4 extra batteries to keep you going. A low battery indicator light on the collar will flash when batteries are running low. EFFORTLESS INSTALLATION: Because there are no wires to bury, installation is a breeze. Just plug in your PetSafe wireless fence for dogs, set the size of your circular boundary and put the wireless dog fencing collars on your dogs. They are ready to be trained!