ALUMINUM TRANSMITTERS ARE NOT FOR USE ON RVs, 5th WHEELS or CARS/TRUCKS WITH BRASS OR STAINLESS STEEL VALVE STEMS! FOR YOUR TOWED VEHICLE ONLY: If your towed vehicle (car, SUV or light truck) was manufactured after 2007, it may have a built in TPMS and aluminum valve stems. If so, you will need aluminum transmitters for your towed vehicle. PLEASE CHECK TO SEE IF YOU HAVE BRASS OR ALUMINUM VALVE STEMS. “Unlike” metals (brass on aluminum) can fuse and corrode.