I have two used TPMS units. I was going to buy two more to complete a set for my winter wheels but I decided against it. They don't have the screw on caps and one needs a valve core but those should be replaced when re-mounting valve stems anyways and they are pretty cheap. I think companies sell the rubber o-ring, valve core and cap as an inexpensive little kit. You can find them on the web. Anyhow, I am asking $50 for the pair.