Essential Piece to the Puzzle!| This is great to have with the HEPA filter and your machine. Essential! We run it under water to wash away the debris it collects once every few months. Let it dry and then it goes back into the machine to a renewed life of use. The replacements are fairly inexpensive, though you have to cut the filter to size your machine. So be sure to keep your old one as a cutting guide. Not sure where to recycle after we are done with it yet.