This is the Lee Neutral Density 0.6 Filter Graduated Hard SW150 (150x170mm Resin) [SW150ND6GH] The Lee Filters range of Neutral Density (ND) Graduated Filters enable the photographer to selectively adjust exposure across the frame without affecting colour balance. They are almost an essential in modern landscape photography on both digital and film cameras and come in a range of strengths denoting the light stopping power of the filter.