Extra TireMinder transmitters for TireMinder A1A, TM66 and TMG400C TPMS. For RV, trailer, motorhome, truck, car or any other vehicle . Replaceable batteries with 9-14 month lifespan (CR1632). It simply replaces valve cap.
All towed vehicles will have either rubber (brass) or metal (aluminum) valve stems. If you have a rubber valve stem, you will need brass transmitters. If you have a metal valve stem, you will need aluminum transmitters. All TireMinder kits come with brass transmitters. If you need aluminum transmitter for your towed vehicle, they can be purchased separately.