These water glasses are made of high quality copper and stainless steel. Copper is slightly soluble in water, so water kept in these glasses. Beside this water kept in this set clears the waste attached with intestinal wall keeps the stomach clean from all stomach diseases, regulate cardiac orders, regulate many other order of body and makes a person cheerful. The inner side where water is filled is made in pure copper while outer side is made in stainless steel. Use these water glasses along with other copper tableware items to get an authentic Indian dining experience. Care Tips:- Clean your copperware by hand and avoid dishwasher as the detergent can cause oxidation leading to permanent damage. Use a solution of equal quantities vinegar or lemon juice and salt diluted with some water at such times but don't use it regularly. Also avoid scratchy cleaners like steel wool. A simple, soft cleaning liquid on soap base, hot water and a soft washing cloth is best for daily use.