 Busbars are produced in a variety of shapes, such as flat strips, solid bars, or rods, and are typically composed of copper, brass, or aluminium as solid or hollow tubes.Some of these shapes allow heat to dissipate more efficiently due to their high surface area to cross-sectional area ratio.The skin effect makes 50–60 Hz AC busbars more than about thickness inefficient, so hollow or flat shapes are prevalent in higher current applications.