Natural antibacterial properties of copper keep the bowl clean and sanitary. Polished copper will patina over time. Clean with hot, soapy water. Manufacturer's limited lifetime warranty. 94% copper, 6% nickel. The Copper and Nickel Bone Pattern Dog Bowl is a pet bowl worthy of man's best friend and your fine decor. Handcrafted of solid copper, the bowl has a decorative fretwork design that is done in an delectable bone motif and given a brushed nickel finish. . . . . .