For those who think that "Big Brother" is tracking them, FasTrak provides a cover which shields the transponder from being read when not going through the toll booth. I don't keep mine on the windshield.. I take it out and put it on the dashboard when going through the toll booth. For someone who infrequently crosses the bridges, it is probably not justified, but I would still have one even if I only crossed a couple of times a year.