This GamColor #1520 Extra CTB Blue 20x24" Cine Filter is used primarily for converting tungsten balanced sources to daylight balance. While a CTB filter will convert a 3200K source to approximately 5500K, this 1520 Xtra CTB (AKA#847, City Blue) is used to either "overcorrect" the source for a blue effect or for dealing with warmer sources below 3200K. It's the approximate equivalent of adding a 1525 1/8 CTB to a 1523 Full CTB.
GamColor Filters are deep dyed in a high temperature resistant polyester with a melting point of 4800°F (2500°C). The GamColor System divides the visible spectrum into nine sections - convenient to the lighting designer. It is a circular classification of colors by hue, referencing the primaries, secondaries and important subdivisions.
Colors depicted may vary slightly, due to differences in computer monitors, printed media, and variances in manufacturer's dyes.