B+W Neutral Density Filter 67mm Neutral Density 0.6-4X Camera Lens Filter, Gray (66-012188) 0.6 ND - 2 f-stops - 75% reduction of light - transmits 25% of the light from the Original scene Filter Factor = 4x Allows creative use of larger apertures for shallow Depth of field or slower shutter speeds to capture motion Blur MRC multi resistant coating - anti-reflection and easy-to-clean coating This filter uses our standard B+W F-Pro filter mount, which has a front accessory thread and is made of Brass.