The Haida NanoPro Variable Neutral Density 1.2 to 2.7 Filter is a variable neutral density filter that provides an exposure reduction of 4 to 9 stops.
The 1.2 to 2.7 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required.
The degree of density is easily controlled by rotating the front filter ring, helping you to predetermine the additional exposure length required. By increasing your aperture or slowing your exposure time, you are able to control depth of field and convey movement more easily.