The Cokin Filter P139 Gradual FLD allows you to reduce a green colour cast at the top or bottom of your image when shooting under standard fluorescent lighting. This allows you to achieve more natural skin tones, for example, in portrait photography.
Cokin P series
You can use the filter with Cokin's P-series mounting system and also in combination with other filters. The filters are flat and square, so they take up little space and always find a place in your equipment.