For metal parts in products, we use copper, brass, and silver. Copper has a good ductility and electrical conductivity. Brass has good hardness which makes parts good mechanical utility. Silver has even better electrical conductivity than copper. We use copper for terminals, brass for mechanical purposing parts like the metal in rocker, silver on the contactors for best electrical conductivity. PC frame has very good insulative to protect user, also has good mechanical utility. It is dampproof, high temperature bearing (650℃). 1.2mm metal steel fixing base with power coating. it’s very durable, excellent resistance to rust-proof, heatproof, fire resistance & insulation.