You have to use feed corn. I have been using corn bags for years to keep my feet warm at night. The last bag I made, which I used for about three years, before the corn decided that enough was enough and it burnt. But it did not catch fire. I do not use any batting in my bags. Cut your fabric about 9 or 10" sq and put 6 cups of feed corn it, sew it up and you're ready to go. I put my on for 2 minutes on high. First bag was gift and I love it.