It's a heat-resistant protective mat with a non-stick Teflon coating. It is placed on the bottom of the oven(or directly on the oven shelves) when cooking to catch food spills and splashes. You can use this oven liner even on BBQ grills, and you will also get it for free as part of our BBQ cleaning service. And best of all it's super easy to clean, both by hand and in the dishwasher.