Most basic underground or wireless pet fence kits come with one waterproof, lightweight receiver and a collar. If the included collar is not the right size for your pet, you can buy a collar at your local pet store and put the receiver on it. For each pet that you wish to keep within the boundaries, you must purchase an additional receiver and collar kit. Any other pet or stray animal that does not have a receiver collar will not be affected and is free to come into your yard.
The receiver is powered by a small 6-volt battery (as seen in the above photo). Most kits come with the first battery, but you must replace the battery at least every three months for it to remain effective.
HINT: When replacing the receiver batteries, visit your local superstore or drugstore and go to the battery aisle. You'll find 6-volt batteries there for much less than in pet stores or home-improvement centers!