I ordered a K&N oil filter the other day from Amazon. I noticed it was made in the USA. When I was changing the oil yesterday, I saw the old filter was made in Mexico (bought about a year ago). The is different construction inside at the bottom. The Mexican filter has a cylinder formed in the bottom while the USA filter is flat, maybe domed somewhat. I don't know what that means, maybe the Mexico filter has a coil spring bypass while the USA filter has some sort of flat valve for the bypass? Earlier in the day I was at Walmart getting oil, and peeked at some other oil filters while I was there. The K&N and the Mobil 1 M1-113A appear identical on the inside. The outer can is a little different. The standard ACDelco PF48E, at just less than $4, has a plastic internal cage that is a lot more open than the metal innards of the others. It's USA made as well. Lightweight and has good recent reviews on Amazon & elsewhere. I got one of them as well because it was cheap, and ended up using it instead of the K&N because I wanted to compare the old/new side by side when I have the chance later.