The Haida PROII 77mm Variable ND Filter is a solid neutral density filter that provides an exposure reduction of 2 to 5 stops. This filter allows you to shoot with a wider aperture or slower shutter speed than normally required. The degree of density can be easily controlled by rotating the front filter ring, helping you to predetermined the additional exposure length required. By adjusting your exposure time or aperture, you can control depth of field and convey movement more easily. The front ring is demarcated with dots for easier, repeatable control over density settings.