<P> When used as a fully supported roof covering, copper is half the weight (including substrate) of lead and only a quarter of tiled roofs . This generally provides savings in supporting structure and materials costs . Copper cladding offers additional opportunities to reduce the weight of copper structures (For more details, see: Copper cladding and Wall cladding). </P> <P> Copper does not require complex ventilation measures . It is suitable for both unventilated' warm' and ventilated' cold' roof constructions . </P> <P> Sensitive electronic equipment are vulnerable to interference and unauthorized surveillance . These products also require protection from high voltages . Radio frequency (RF) shielding can address these issues by reducing the transmission of electric or magnetic fields from one space to another . </P> <P> Copper is an excellent material for RF shielding because it absorbs radio and magnetic waves . Other useful properties for RF shielding is that copper has a high electrical conductivity, is ductile, malleable, and solders easily . </P>

The finish that is most suitable for bringing out the natural color of the stone is a