This is a used working Petsafe Wireless Containment System. Included transmitter, collar, instructions and one battery for the collar.

We used this system and enjoyed it, but switched over time to a buried wireless fence system.

The system works by transmitting a signal out in a radius you set from the base unit. The pet gets corrected when approaching the perimeter. The resulting perimeter is a circle, but none of the properties we used it on had square lots. It still worked well enough we used it at two different homes.