This genuine OLYMPUS accessory reduces lens flare effectively while taking astonishing photos with your underwater equipment and the M.Zuiko Digital ED 30mm 1:3.5 MACRO lens. Furthermore, it blocks aperture and the focal length information from being reflected on the front of your lens in the glass of your housing's lens port. In order to minimize reflections and flare, simply screw the anti-reflection ring into the filter threads of the lens.