Over the last 10 years, there have been a few revisions. Heavy duty canvas was a great addition because it’s harder to scorch. By far, the best addition was reflective heat material. It doubles the heat of the iron! All of the sudden, I could pull my binding through, twice as fast, and still have a crisp, flat crease. This material combination has stood the test of time. I’ve been using them in the same board for the last 7 years!