16 Oz. Solid Copper "Happy Birthday" Moscow Mule Mugs, Set of 4

It’s solid copper, until you get to the nickel lining. How thick is the solid copper? What’s the difference between this and a copper plated nickel mule?

Per the vendor: The cup is solid copper. The nickel lining is there because copper tarnishes very easily. Since the inside of the mug holds the liquid the nickel lining will help to keep the mug looking new for much longer.