Product review (4 stars): These were actually purchased for use in my sewing/quilting room ...
These were actually purchased for use in my sewing/quilting room as a smooth and slick surface to slide a quilt sandwich over while machine quilting.  Cannot review as to their effectiveness for that because I haven't used them yet.  I did fit one in my oven and have removed it.  Not for sure but I felt they were impeding heat from getting to items I was baking, or I could be a lousy baker.