The Rosco R3442 is a yellower (or less red) version of 1/2 CTO. Converts 5500K daylight to 3800K. Deep-dyed base. (Transmission = 73%). Roscolux Color Filters are made especially for high heat quartz and incandescent fixtures. Use in front of theatrical, display and studio lighting luminaires for color washing and blending.There are no set rules for color selection. The application listed is offered as a suggestion only. The type of lighting fixture and intensity of lamp being used are variables to be considered. Try different color gel combinations to obtain your desired effect.