Prism film / BEF/ Brightness enhance film This kind of prism film has an applied thickness of 200 mm and can be used to enhance almost any diffuse light source. Its monolithic, polycarbonate construction makes the film ideal for high-temperature applications, such as avionics, automotive and instrumentation/ navigation systems.And applied thickness of 180 mm and can help increase display brightness while providing high temperature stability in demanding display environments. Its monolithic, polycarbonate construction makes the film ideal for high-temperature applications where a slightly thinner enhancement film is desired.