Grey Neutral Density filters compensate for bright light. By under-exposing the sky, they give a better relief to the surfaces and colors of landscapes and architecure. They are indispensable in summer, for seaside and mountain photos. They are available in six choices to cover every situation. 120 - 2X graduated neutral density filter reduces the light 1 stop 121 - 8X graduated neutral density filter reduces the light 3 stops. 121L - 2X Light starts with the same neutral density as 120, but feathers the grey almost from the color edge and more gently graduates to clear. One stop of compensation. 121M - 4X Medium is the same gentle graduation as 121L but with twice in dens ty. Requires 2 stops of compensation. 121S - 8X Soft is twice the density of 121M and the graduation extends to 3/4 of the filter. Requires 3 stops. 121F - 8X Full is the same as 121S except that the neutral density grey cover the entire filter. Requires 3 stop