New in Box Set of 2 Solid Copper Moscow Mule Mugs – 16-OZ #428. This set of 2 Moscow Mule Mugs are constructed of solid copper with nickel lining and solid brass accents. This unique and stylish copper mule mug is constructed of solid copper with nickel lining and solid brass accents, the made-to-last mug features a coating of resilient lacquer that resists tarnishing for lasting beauty and luster.