Steel bars used in pickups can act as a pole piece for a particular model pickup. The steel bars can be flat or radiused to the fingerboard or bridge radius. Some blades can be laminated with a number of thinner blades to help reduce eddy currents within the coil. The laminated blades and steel bars need to be properly potted in a material to help reduce or eliminate unwanted microphonic feedback. Steel bars can be machined to the desired shape and plated to eliminate rusting or oxidation from continuous wear and tear and exposure to moisture. Most bars are made from carbon steel that will conduct the magnetic field to the strings and special stainless steels with magnetic properties can be used without plating.