WiFi Rechargeable Pet Fence uses the latest digitally encoded WiFi signal technology used in advanced wireless communications with the 802.15 WiFi protocol. Unlike other fencing technology, the Wire-Free Smart Station and Pet Link collar are both connected by Transceivers - highly integrated signal chips that constantly links the distance between your dog and the Smart Station.
http://www.petstreetmall.com/Portable-Containment/7490/619/Wireless Dog Fence and with FREE SHIPPING on the Petsafe Wireless Fence.