http://www.mydoggiesupplies.com/18g-Twisted-Wire-for-Underground-Electric-Dog-Fences.html
18g Twisted Wire for Underground Electric Dog Fences - My Doggie Supplies
Additional twisted wire for use in underground electric dog fences. Twisted wire is used to cancel the signal of your electric dog fence to allow your dog to pass through certain areas without correction. 50' of 18g twisted wire