This 15.5 Qt pan is constructed of low carbon steel with porcelain glass coating. The glass like surface is inert and does not react with or alter the taste of food, color or healthfullness. Even the most stubborn foods clean up easily with warm soapy water. The porcelain surface will protect the flavor of delicate dishes and creates a durable, chip resistant pot that lasts most families a lifetime. Perfect for cooking tamales and menudos. Comes with insert. Porcelain enamel is the result of fusing powdered glass to a substrate by firing, usually between 750 and 850 degrees Celsius. The powder melts and flows and hardens to a durable vitreous coating on a carbon steel core. It creates a smooth, hard finish that won’t burn and resists staining. It’s also non -porous so it won’t trap odors or food particles and provides a low coefficient of friction – meaning that it cleans up easily and, it is corrosion and chemically resistant so it will last a long time. When fired, the vessel is placed on pins so the bottom and sides are hardened during the firing process into one smooth laminated glass surface. You may notice slight pin indentations where the glass has flowed around the pin that supports the base during firing. The pin marks do not compromise the finish or performance of the vessel in any way but you should take additional care in handling if using on glass top stove.