I don't see anything free about that filter wool. It should work but it strikes me as a very expensive alternative at the quoted price. When it comes to making a final filter out of filter wool, the polyester fiber used to stuff pillows and kids stuffed animals makes great filter wool and costs a lot less. I use the stuff that I get in a local sewing shop for mine. It costs about 1/4 of the price quoted in that ad by the time you pay P&P.