Calphalon Contemporary Stainless Steel Cookware, Flat-Bottom Wok, 13-inch A heavy-gauge aluminum core is sandwiched between two layers of stainless steel by means of high-heat, high-pressure impact bonding for extreme durability. Aluminum core provides superior conductivity and even heating for excellent browning and control of the cooking process. Non-porous stainless steel cooking surface is safe for use with all utensils. Adapted from a traditional round-bottom wok, this flat-bottom wok has a wide cooking surface ideal for stir-frying on gas or electric ranges. The domed cover is perfect for steaming and simmering soups. Long, brushed stainless steel handles stay cool on the stovetop. All cookware is dishwasher-safe and carries Calphalon's full lifetime warranty.