Yea, I bought a couple of the "made in the USA" AC filters for my new Corolla I just bought, they are part number AC1233. They all rattle when you shake them. I thought hmmmmmmm, so I went to a couple other parts stores to see if others rattled and most of them did. What could be rattling inside of an oil filter and should I be worried? Also, I noticed that for the 1233 at least, every one at every store I went to, even Advance Auto parts, were the made in the usa ones, not the ones made by Champion. All the other AC filters at Advance were Champion filters, made in Mexico.