If you own an Ooni 12, you need this. Living in Canada temperatures outdoors can fluctuate significantly, the cordierite stone that comes standard on the Ooni takes ages to heat up and you get inconsistent cooking between the toppings and crust. I'm on a few Ooni Facebook groups and the complaints about the Ooni 12 are all the same, long heat up and recovery, burnt toppings with undercooked crust. Some recommend adding doors to the front or using the "secret low setting" while cooking, but that's all nonsense and a design flaw with the Ooni 12, but it's a $400 pizza oven so I don't expect it to be perfect, but it can be. I've had the Atlas steel for my Ooni 12 for over a year and it makes perfect pies. It fits perfectly, heats up quickly but more importantly transfers heat quickly and recovers fast. I've had a few nights where I was putting out more than 10 pies, one after another and there was no deviation in the cook. I can leave it on a consistent temp and on those cooler or winter nights the pies don't suffer. The is the best upgrade you can make to pizza night.