B+W 67mm MASTER Neutral Density 806M (3%, 6 stop) Filter, darkens the subject area by six f-stops without changing its color. Ideal for Landscape Photography, the 806M is finely polished glass and lasts longer than easily scratchable plastic substrates. It is used when no suitable aperture can be selected in bright light or when a specific, short DOF is required. With this filter, running water is rendered hazy and soft, and a tripod is recommended.