It's only because you're so young and good looking that you don't recognize the name "Flame Tamer." It was a little heat diffuser, stuffed with asbestos, it cost nearly nothing and worked like gang-busters. If you were only old enough to remember when a Chemex coffee pot sat on every stove, you'd remember a Flame Famer beneath them on the glass stoves (and a little copper ring on the electrics).
Guys as old as Old and me think of Flame Tamer as the generic for diffuser.
Asbestos. Who knew? Well actually the people who were selling it to us knew. But that's a different story.
Anyway, I think Kuhn Rikon owns the rights to the name and make a good diffuse under it. Not cheap though. 2 matches for: flame tamer