Who cares who makes a particular filter. They are made to someone's spec be it a top spec like Mobil 1 or Amsoil or a value filter like a Supertech. Almost all of these companies have the manufacturing capabilities to turn out a great or ________ filter. Its all in the specs for the filter. You can bet that Mobil and Amsoil have done or paid for testing to be done on these filters and also instected and cut apart several of the filters. Amsoil does not make the base stock for their oil either, but do I really care who they buy it from. They test the base stock at delivery before its added to their tanks and they do several more tests during the manufacture of the oil. Sears (Kenmore) does not make any washing machines, but contracts out to have them made to their spec. I believe they have even changed over the years. And maybe not all Kenmore models are made by the same company. You are buying a Kenmore name and expect a certain level of quailty regardless of who made it. Same for the filters.