Bob;
I replaced mine with a "Cucina Pro". I actually talked to the people at Cucina and they told me their stone is made of the same material used to line wood fired ovens. It is 3/4" thick and round with a diameter of 16 1/2". We did a pizza party the other evening and I love the way it works. The greater thickness takes a bit longer to heat but I can do at least six pizzas before I would need to add coals ( maybe more ).