90% STAINLESS STEEL 10% COPPER PLATED - The moscow mule mugs is made of stainless steel on the inner layer and copper-plated on the outer layer, perfectly finished. Mug with the special coating, the mugs are time resistant and durable,great for iced tea chilled, iced coffee, iced tea and any vodka, beer, gin, rum, tequila, martini glasses, or whiskey mixed drinks drinking set.