These are light balancing filters used to increase the color temperature slightly for a cooler (bluer) tone.
Corrects the tendency toward reddish tones. For example, select the 82B when using tungsten Type B color film (3200oK) with ordinary household 100W electric bulbs (2900oK). These series filters are also used to prevent the reddish tones in early morning or late evening light for natural skin tones. These filters can be used together, but do not mix 81 and 82 series filters since they cancel out each other.