Base materials are important parts of RF applications; they prevent EMI interference. Metals vary in their resistance to corrosion, and connector parts are plated with different metals for various reasons, including to improve electrical and thermal conductivity, to improve contact between conductors, and improve the solderability. Gold is an excellent conductor and resistant to corrosion, but expensive, so thin layers are used on top of other metals. This makes it possible to take advantage of the electrical and thermal properties of the plated metal and keep costs down. Nickel is harder than gold and improves the wear resistance and mating cycle life of connectors. Passivated finishes use a chemical process to plate with gold or stainless steel to prevent corrosion. White bronze is not actually bronze, but an alloy of varying amounts of copper, tin and zinc which has an aesthetic finish similar to stainless steel. White bronze plating offers many advantages over nickel or silver plated connectors, which include improved electrical and intermodulation performance, better wear characteristics in harsh conditions, and low insertion loss compared to nickel. Brass is commonly used for the connector body material. Brass resists against industrial and marine atmospheres. It has a low electrical conductivity and offers high stability, high melting temperature, and fair corrosion resistance, especially when the material is used for the outer component of an RF connector. It is a softer material that is easier to machine than other metals. Stainless steel is formulated not to rust or corrode when exposed to moisture. It is a hard material that is extremely durable for connector housings, although not for contact parts because of its hardness and relatively low electrical conductivity. It is higher in cost than bronze or brass, but features high stability, durability, and outstanding corrosion resistance. Die casting is used on some high volume products to save cost. Die casting is a manufacturing process for producing accurately dimensioned, sharply defined metal parts, which is accomplished by forcing molten metal under high pressure into reusable metal dies.