The Kodak 4 x 12" #92 Red Special Color Effect Wratten Gel Filter is used for densitometric measurement of color films and papers.
Most Kodak gelatin filters are available in 3 x 3" (75 x 75mm), 4 x 4" (100 x 100mm), 6 x 6" (150 x 150mm), and 14 x 18" (350 x 450mm).
Wratten 2 Improvements
More rigid/durable
Easier to handle
Color consistent today, and 6 months from now as well
Wratten 2 Optical Filters are less sensitive to humidity, less prone to static cling