Stainless steel mug with a cork base, holding 12 ounces This mug, constructed of double-walled stainless steel and featuring a cork base, is an excellent choice for those who want to enjoy both hot and cold beverages. The cup's built-in cork bottom serves as a coaster and prevents the cup from sliding around on smooth surfaces. It will keep your beverages hot for up to eight hours and cold for up to twelve. The following colors are available: black, gray, navy blue, and white. This item does not contain any BPA, phthalates, lead, or other harmful chemicals. They are constructed of food-grade materials that have been FDA-approved and passed California Proposition 65.