Primo Natural Finish Ceramic Baking Stone, 13-Inch, for Oval X-Large and Large, Junior and Round

Which Primo grills does this stone fit?

Four of them: the Oval X-Large, Oval Large, Oval Junior and Round, all named on the listing. It is the smaller of the two natural finish diameters, and along with the 13-inch glazed stone it is one of only two stones whose listing covers the Junior.

What am I giving up by buying the smallest stone?

Baking surface, and nothing else the listings state. A 13-inch disc handles personal pizzas, flatbreads and small loaves comfortably but will not take a large pie. If most of your baking is for a household rather than a crowd, that is often all you need.

Is this the same as the glazed stone?

Same diameter, same four grills, different finish. One is glazed and this one is not, which is exactly what the titles say and all that is published about the difference. Buy on finish preference and price; this natural version is the lower-priced of the two.

Do I put it straight on the cooking grate?

It needs to sit on something stable and above an indirect setup, not directly over open coals. The usual arrangement is a heat deflector low in the grill to block the fire, then the grate, then the stone on top with air able to reach around it.

What should I cook first?

A simple pizza with a thin base and restrained toppings. Wet toppings release water onto a hot surface and stop the base crisping, so the first attempt tells you far more if you keep it plain. Once that works, bread and flatbread are the obvious next steps.