This allows switches and crossings, which are generally composed of high manganese steel, to be effectively welded to carbon steel rail with the use of a stainless steel insert, while keeping the desired mechanical properties of both the rails and the crossings intact. The ability of this single process to weld many different metals, with simple parameter adjustments, makes it very versatile. Flash welding is also used in the metal building industry to increase the length of the angle iron used to fabricate joists. The aluminum industry uses flash welding to join aluminum, steel, and copper in various current-carrying conductors called busbars. The steel is used for strength, the copper is used for conductivity, and the aluminum is used for its combination of cost and conductivity.