The Black & white filter kit includes: yellow (001) orange(002) red (003) green (004) 4 - filter cases Black & white filters give photographers the creative freedom to control contrast in an image for creative effect. The RED filter will turn blue skies (complimentary color) almost black creating dramatic contrast between the sky and clouds. Use the same red filter when photographing a red rose (analogous color) and the rose will look almost white. Yellow is used by portrait photographers because it lightens skin and reduces the appearance of freckles and blemishes. While this kit is a must for Film photographers, many digital shooters will use these filters to shoot Black and white in raw so that they can see the result in the field then make fine-tuned adjustments when post processing.