Gray filter with Helix MagLock filter system. Gray filter with a diameter of 101 mm. Helix MagLock magnetic mounting system. Optical glass with multi-coating. Front and rear defender caps. Filter ring made of brass. Rubber frame insert provides more grip. 1x ND1000 filter, 1x front, 1x rear defender. ND filter - extend the exposure time. A neutral density filter (ND filter) or gray filter blocks a portion of the incoming light. With a gray filter, you significantly extend the exposure time, achieving effects like blurred water or preventing overexposure in bright sunlight with an open aperture.