Vitraluxe Heirloom collection is twice fired premium china that is fired at a high temperature to create a reinforced stoneware that is durable, break and chip resistant. It is reinforced with alumina oxide for durability. Make things mid-century modern with Heirloom dinnerware. Unique forms and matte finishes mean these pieces are perfect for daily use as well as special get-togethers. Dishwasher, microwave and oven safe. This set includes 4 - 11.5oz tapered mugs.