This 3-stop, 58mm Kase ND Filter with Magnetic Ring provides an exposure reduction. Its 0.9 optical density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed without overexposing your image. By slowing your exposure time or increasing your aperture, you are able to control depth of field and convey movement more easily. The included magnetic adapter supports stacking up to four Kase Wolverine filters, and accepts 58mm lens caps.