It's supposed to be used for simmering.

I use it so that my stovetop expresso maker doesn't fall between the grates. Given that 98% of the households in Italy have these stovetop expresso makers (mine's a Bialleti), I don't get why there is so much space between the grates, allowing the expresso maker to fall in. Darn good thing I have that simmer ring!!

Love my Berta, tho!

We thought it was a simmer ring, but it makes sense for smaller pans as well.

Mine has only been installed since Friday, so I don't have a full review yet. It is beautiful to look at, though.

This is an old thread, but it's worth reviving it to mention that you CAN find a thingy-ding to place over your range top grates so that your espresso pot won't fall in. The magic phrase to put in your search engine is (drum roll, please) "gas ring reducer." Amazing how much work it took to figure that out!

Here is a link that might be useful: Ilsa Gas Ring Reducer

Just toss the silly ring out. You cannot beat Starbucks coffee anyways.

Do NOT toss the thing out!!! It's very helpful in that it raises a pot slightly, allowing an even lower temperature to be achieved: this is perfect for cooking rice, for example, or a delicate sauce. I use mine so much, I acquired a second from Bertazzoni, to use on the inner ring of the double burner.
Although it seems so many forum posts are about finding the highest power appliance possible, I find I need the lowest possible for many things, far more often that I need high power (except for my wok).