37mm ND Fader Neutral Density Adjustable Variable Filter, ND2 to ND400 Filter 1. Offers ND2-ND400 neutral density. 2. Smooth rotating to desired density. 3. ND filters (Neutral Density) reduce the amount of light reaching the film without affecting the color. Can be used to enable slower shutter speeds. Also can be used to better separate subjects from the background by allowing wider apertures, effectively decreasing depth of field. Great for portraiture and outdoor scenes. 4. Slim profile design. Thin filters are essential for avoiding vignetting when shooting at wider angles. 5. This filter is mounted on a rotating frame allowing the user to determine the desired amount of light transmittance by rotating the filter. 6. These filters are double threaded allowing additional filters to be mounted one over the other. 7.Use one at all times to protect your delicate lens from dirt, scratches and accidental damage. Better to scratch or break a filter than an expensive lens 8. Large aperture is available to creat depth of field easily. 9. Suitable for dynamic screen, waterfalls, streams, waves, etc. 10. Filters Frame is made of aluminum metal. Multicoated lens for reduced lens flare and ghosting caused by reflections.