Old Dutch 2P537 Whiskey Tumbler, Copper Set of two 11 oz. Whiskey tumblers Two-ply technology: a layer of solid Copper bonded with a layer of 18/8 stainless steel. Get the cooling benefits of Copper with the durability of stainless steel These made-to-last tumblers feature a coating of resilient lacquer that resists tarnishing for lasting appeal