With a light intensity reduction of ten f-stops, this B W Neutral Density Filter has a slightly stronger warm tone than the ND 106. Its principal field of application is the observation and documentation of industrial processes with extreme brightness, such as steel furnaces, incinerators, glowing filaments in halogen- and other bulbs. The filter factor is 1000x. Single Coating Each glass surface is vacuum coated with one layer of Anti-Reflection coating. This single layer helps to prevent internal ghosting and reflections. It also improves light transmission from approximately 92% (uncoated glass) to over 98%. Mount This filter uses our standard B W F-Pro filter mount, which has a front accessory thread and is made of brass. Compared to the earlier standard mount introduced in 2001, the F-Pro mount has become thinner. Now it can be used with wide angle lenses, including most 24mm focal lengths on a full frame body, without vignetting. Another advantage of the F-Pro mount is it's modified retaining ring, which is no longer threaded in from the front, but holds the filter glass in place from the back. When removing a filter or lens hood that has been screwed on too tight to the filter, the retaining ring is not at risk of loosening. NOTE: diopters are mounted in the older mount due to glass thickness.