These soufflé cups are 100% pure copper and made in Wisconsin.
Copper will not rust or corrode.
Care Instructions: Copper straws work best when used with mid-range pH liquids such as water, milk and non-acidic beverages. Do not put in dishwasher; the soaps are too abrasive for pure copper. To shine up copper after time and use, consider a ketchup bath or lemon, flour and vinegar rub. *care instructions also included with the order*