Silicon brass are part of the subgroup of high strength brasses. These materials contain less than 20% zinc and less than 6% silicon. The silicon brasses are solid solution strengthened. These silicon brasses are typically chosen because of their high strength and moderately high corrosion resistance. The conductivity of the silicon brasses is much less than that of unalloyed copper. The silicon red brasses are used for valve stems where corrosion and high strength are critical. The wrought silicon red brasses are designated as UNS C69400 through C69710. Included in this category are the silicon red bronzes. These alloys are similar to the silicon red brasses except they contain very low concentrations of zinc. The silicon red bronze alloys are designated UNS C47000 through C66100. The cast silicon red brasses are C87300 to C87900. Silicon brass castings exhibit moderate strength and very good aqueous and atmospheric corrosion resistance. They are used in applications such as bearings, gears, and intricately shaped pump and valve components.