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. Brass filter ring. Rubber frame insert provides more grip. The Helix MagLock filter system is designed to eliminate the hassle of screwing and unscrewing filters while providing a filter that securely locks in place after installation. Unlike other magnetic filter systems on the market, Helix offers an absolutely secure connection through the quarter-turn magnetic locking mechanism, allowing for lightning-fast attachment and removal of filters while ensuring they stay in position even in the most demanding shooting situations. These filters won't go anywhere until you remove them from your lens. With available brass thread bases of 67mm, 72mm, 77mm, and 82mm, Helix easily covers your entire lens arsenal. 1x ND64 filter, 1x front, 1x rear Defender ND filter - extend your 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 of the image in bright sunlight with an open aperture.