Production companies and photographic markets use these plastic filters to add color to stage scenery and to provide color correction for theatre, film, and television. Gel creates mood by changing the color shade of light.
There are two widely-accepted gel manufacturing processes: double-coated and deep dyed. Apollo gel is double-coated because many designers appreciate the color consistency found in the double-coated process.
A total of 140 colors are available.

Gel Conversion Chart