I bought this over 30 days ago and now two out of four caps are leaking. I've had three flat tires (two with the same tire) in a few months and nothing has been found. Eventually the body shop tested them with a soapy water spray and found that two of the four caps were starting to leak. I can't get them back through Revain now and I don't have $18. Don't buy more and having two out of four of these things in one car looks weird. Overall not worth buying.