Key Benefits Waterproof receiver collar is for dogs 8 pounds and up, fits neck sizes 6-28" Covers up to 1/3 acre with included wire, expandable up to 25 acres with additional boundary wire (not included) 4 adjustable levels of static correction, or tone-only mode alerts your pet with a beep. Safety shut off stops correction after 30 seconds. Correction increases if your dog tries to run through the boundary zone. Collar uses PetSafe RFA-67 battery (included) and has a low battery indicator Works with multiple dogs and cats (additional receiver collars required) What's Included Transmitter with power adapter and mounting bracket, receiver collar with RFA-67 battery, test light tool, operating and training guide, (50) boundary training flags, 500 feet of boundary wire, wire nuts and gel-filled capsules.