Wow, I am facinated by that filter. It appears to be a real "depth" filter. I am wondering if the seal across the end is because it has some moisture absorption capacity and is sent out "dry". I think I will try to find one of them to play with. Any way to determine if there is a cross with any american made filters? I guess I will go to the store and find what AC filter that car takes and then look around for any others that take it. The top and bottom construction are also quite interesting. Thanks a lot for that post. RW