The Petsafe Stay and Play Wireless Fence Transmitter. You Can Increase The Coverage Of Your Petsafe Stay and Play Wireless Fence By Using Additional Transmitters. It Is Simple To Expand The Containment Area With The Purchase Of Additional Transmitters By Overlapping The Boundaries. You Can Use Another Wireless Transmitter With Overlapping Boundaries Of At Least 5-10 Feet To Increase The Size Of The Pet Area. Features: Use Multiple Transmitters To Create Overlapping Containment Areas Allowing Your Dog Greater Mobility The Signal Field Can Be Adjusted Anywhere From A 5 To 105 Feet Per Transmitter Creates Multiple Intersecting Circles, Two Transmitters Would Create A Boundary In A Shape Similar To The MasterCard Logo The Signal Is Canceled Where The Circles Intersect, Allowing The Pet Access To The Entire Area Includes: Wireless Fence Transmitter Power Adapter.