Product review (1 stars): buy these, not the cheaper ones. UPDATE: NOT ANY MORE.
these are the ones to buy. as others have pointed out, there are similar looking filters for slightly less money. i bought Those last year... won't do that again. these are thicker and work better.

UPDATE: these have  been changed and no longer work AT ALL. as someone else mentioned, as soon as you wet them, they become so limp you can't put the top on the machine without mashing them down. totally useless.