Product review (3 stars): Affects oven performance
I was surprised by how well they unroll and lay flat, no worries there. Would be excellent on an old school oven with an exposed lower element. If you have a hidden lower element unfortunately this really affects the way things cook in my experience. I've got it sitting on a rack in the lowest position (can't put directly on the oven floor with a hidden element it'll damage the element). Typical box frozen foods take about 25% longer to cook vs time on box. Cooking for baked items also seems less even when the sheets are in. I store it out of the oven and only use it for pizza or other messy things.