There are two main types, these intended for general industrial use and those for specialized applications. The former include greases thickened with silica and clay ( Bentonite) and organic derivatives,such as terephthalamates, diamido dicarbonyl and aryl substituted ureas. High temperatures, mechanical stability, water resistant etc. suggest that they are multipurpose greases with a wider scope than soap greases. However, they have not made any great impact on the market. The type used for specialized applications includes greases made from the dye stuffs indanthrene and phthalocyanine which are generally combined with synthetic fluids, such as diesters and silicones and hence are very expensive. One such product is claimed to operate between - 75ºC and + 320ºC.