The Cool Blue hard edge color graduated effects filter gives a steelier blue effect than the Blue filter. They are available in 3 densities, 1,2 and 3. These filters are clear in the bottom half of the filter with a gradual transition to the color effect in the top half. They are primarily used for skylines of landscape shots. Graduated filters are available in Soft Edge or Hard Edge varieties. Soft edge grads have a smooth transition from clear to ND. Hard edge grads have a more defined hard lined transition and are usually used for longer focal lengths. Different graduated color filters can be used in combination together or with solid color or neutral density filters to give interesting bespoke effects. This 85mm filter is usable with Hitech 85mm holder systems or any 85mm (3.35-Inch/P Size) holder.