I've seen this around for a few weeks now. It's a flexible food grade silicone mat with holes in it. The mat is for "Delicate fish and sliced veggies. No more sticking. Food won't fall through the grate" It's used with indirect heat.
Decided to take the plunge (it was on sale, it's usually around $20) as I was grilling some very expensive wild salmon for guests and didn't want it to fall apart (ok, maybe that was just an excuse).
I'M A CONVERT. The mat worked perfectly, fish had a wonderful grilled flavor (just seasoned with evoo and s&p), nice grilled appearance. I then used it to grill some very very skinny asparagus spears .. perfect again.
Has anyone else used this, seen it, care to report on it?