The Lee Seven5 0.9 ND Hard Grad Filter helps to darken specific areas of an image, such as bright skies, while allowing for a normal, unaffected exposure in the other regions of the image. The filter is densest at the edge and tapers to clear by the middle, with a hard-edged line of transition between the density and clear areas. Neutral density filters do not affect the coloration of the image and the 0.9 density provides a 3 stop reduction in light from entering the lens.