The Double Classic Black Soft Filter combines the benefits of the Classic Soft filter, in various grades from 1/8 to 2, with the effects of the Black Frost 1/4 filter, double the strength of the Black Frost 1/8 effect of the regular, Classic Black Soft Filter.
The Double Classic Black Soft combination always has the 1/4 grade on the Black Frost effect, while it's grading 1/8, 1/4, etc. reflects the Classic Soft effective grade of the combination.
This filter is ideal for infocus diffusion plus a heavier Black Frost effect, without filter stacking.
(The Classic Soft filter is a subtle and effective softening filter that can be used freely without fear of compromising the high quality of modern lenses, while the Black Frost filters flare highlights, mutes colors, and tones down contrast, while retaining rich blacks, primarily a styling, or mood modifying filter.)