This 4-stop, 67mm QuartzLine Solid ND Filter from PolarPro is an ND filter with a 16x filter factor that provides a 4-stop exposure reduction. Its 1.2 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 can control depth of field and convey movement more easily. Neutral density filters do not affect the coloration of the image and are ideal for pairing with other filters.