Calphalon Classic Bakeware 12-by-14-Inch Nonstick Medium Insulated Cookie Sheet Medium, nonstick cookie sheet made of heavy-gauge, aluminized steel Heavy-duty construction means no twisting or warping Insulated layers promote moist, chewy results every time Oven safe to 450 degrees F; not broiler safe; not dishwasher safe Measures 12 by 14 inches; lifetime warranty