The Cavision 4 x 4" Neutral Density 0.6 Filter is a solid neutral density filter providing a 2 stop reduction in exposure. This 0.6 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. By slowing your exposure time or increasing your aperture, you are able to control depth of field and convey movement more easily. Neutral density filters do not affect the coloration of the image and are ideal for pairing with other filters.ND filters come in increments of 0.3, where each increment is equivalent to one stop. For example, if a scene is overexposed by 2 stops use a 0.6 ND filter to get proper exposure.