William Sheppee 16 Ounce Copper Moscow Mule Mug - Set of 4 Stainless Steel 50%/Copper 50% Imported A Novelty for Every Bar - Bring the legend of the Moscow Mule to the party with a 12 oz. double wall copper mug. Stainless Steel vs. Solid Copper  18/2 Stainless steel interior does not rust or scratch and eliminates metallic taste. Freezing Insulation of Cold Drinks  These double wall copper cups contain both stainless steel and copper, creating extra insulation and keepingdrinks cold until the last sip. Five-Star Materials & Craftsmanship  Solid copper exterior is hand hammered with slight variations in shape and finish, improving cup durability and display. Product Care - Hand wash. Use mild detergent and soft sponge only. Do not scour with abrasive sponge, pad or paper towel. Wipe clean with soft, dry towel only.