If it's the teflon/silicone liner..it's not supposed to go on the bottom of the oven..it's to go on a shelf below the item you are baking/roasting. Even aluminum foil will melt if it's placed on the very bottom of the oven. The heating elements(electric) or gas burners are underneath the metal plate on the bottom of the stove. If you have an electric oven where the elements are visable at the bottom of the oven you would place the liner underneath it.