The Tiffen 4x5.65" Soft Edge Graduated 0.9 Filter (Horizontal Orientation) is a three stop graduated ND filter with ColorCore Technology that is at the densest at the top of the frame, helping darkening skies. It is called "soft-edge" because it tapes to clear with a soft-edged line of transition. A more subtle darkening of the top of the frame can be obtained with the 0.6 Tiffen graduated ND.