Aluminium foil is aluminium prepared in thin metal leafs, with a thickness less than 0.2 mm / 0.008 in, although much thinner gauges down to 0.006 mm are commonly used. Foils are commonly gauged in Mils. The foil is extremely pliable, and can be bent or wrapped around objects with ease. However, thin foils are fragile and easily damaged, and are often laminated to other materials such as plastics or paper to make them more useful. It replaced tin foil in the mid 20th century.