The NiSi 100x100mm Nano IR Neutral Density Filter - ND32000 (4.5) - 15 Stop is a Neutral Density (ND) filter that uniformly reduces the amount of light entering the lens. ND Filters can enable greater motion blurring and image detail by allowing a large aperture and a slow shutter speed. ND filters are also helpful when the contrast between the highlights and shadows is too high to get quality exposure. A 15 stops filter can be used to achieve very long exposures in the middle of the day and with this filter, exposures upward of 5 minutes can be achieved even during bright sunshine.