The Beats® headphone frame is made from strong anodised aluminium. Aluminium, a strong yet lightweight metal perfect for making wearable tech, is anodised to increase its ability to resist wear-and-tear. The aluminium headphone frame is dipped into an electrolytic solution with a ~20-volt direct current flowing through it. Bubbles of hydrogen form at the cathode, and bubbles of oxygen form on the surface of the headphone. This oxygen gas buildup quickly oxidises not only the surface of the headphone, but deep into pores in the surface, which give the frame very high resistance to corrosion. ●