An 82a is a light balancing filter used to increase the color temperature slightly for a cooler tone this light blue filter absorbs the excessive yellow red light from daylight in the morning and evening hours and keeps skin tones close to natural whereas the 81 series of filters creates a feeling of warmth the 82 series creates a feeling of coolness this filter measures 85 x 85mm and fits the cokin p series holder filter factor 11 13 stop