Each bowl is made of high-quality heavy gauge steel. The mixing bowls are porcelain enamel exterior and interior for high luster and easy cleaning. Their bowls are deeper than standard bowl sets, allowing for larger servings. This set contains sizes that gives you much more flexibility, and less mess, satisfying your demands for mixing large batters, tossing salads, washing vegetable, marinating and storing, etc. A flexible translucent plastic keeps your food fresh, tight-fitting lids are great for food storage. A deepening basin type is ideal for mixing ingredients without any splash. The colored bowls feature a soft interior and fingerprint-proof satin exterior, Which are simple to hand wash only. They highly recommend hand washing the lids to preserve the strong seal of the lid to the bowl. This set is a refrigerator, and freezer safe. They are stackable and designed to be nested for the perfect fit in your kitchen cupboards to save your kitchen space.