The 3 x 3" Cavision ND Glass Filter provides a 2-stop exposure reduction. 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 increasing your aperture or slowing your exposure time, you can 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.