that's why i posted the vids on the gas tracker boots. when speaking with the rep the other day i asked about prices? pretty spendy so mainly facilities are buying them. the rep did say that there was on construction company (in dallas i believe) that owned at least 1 unit, maybe more. he was also telling me that PG&E was acquiring a few for their facilities. basically you have to have access to the gas itself, the unit connects into the system where it introduces a low frequency into the gas which is located via the receiver. these will allow the user to locate pipe without the aid of a trace wire. years ago we were required to install trace tape over water, sewer and gas on public works projects. i still have a partial roll of water tape that i use on occassion since you can use a ferro magnetic locator to find the tape in lue of an electromagnetic locator.