The Instant Fence Transmitter is for the PetSafe Wireless Dog Fence. This transmitter is compatible only with the Instant Fence Receiver. The part number for this dog fence transmitter (found on the back) is IF-100.

Increase Your Wireless Dog Fence Coverage with Additional Transmitters

The range of The PetSafe Wireless Dog Fence can be increased by using two or more transmitters.  This creates intersecting circles and the signal is cancelled where the circles intersect. This allows your pet access to the entire area. One additional transmitter would create a boundary that is up to 180 feet wide and up to 330 feet long.