Often it is necessary or desirable to balance the light intensity in one part of a scene with another. This is especially true in situations where you don't have total light control, as in bright contrasty landscapes. Sometimes it is also desireable to add color to part of the photograph. For example, to add blue to only the sky. Hitech Grad Color filters are part clear and part color. They are available in grades of 1 through 3, with 3 having the darkest color.
Hitech graduated resin filters are 4 x 5" (100 x 125mm) x 1.5mm thick. The 5" length allows for adjustment of the filter within the holder.