This ProMaster HGX Prime VND filter provides 1.3 to 8 stops of light control by rotating its ring. Mechanical "hard" stops at each end of the filter's density range prevent bypassing the minimum or maximum useable density. A small, knurled knob provides a tactile experience making it easier to rotate the filter quickly and smoothly, simply by touch. This knurled knob is removable if you prefer not to use it. White lines on the filter's ring indicate its density setting at each full stop. These lines represent densities of 2, 3, 4, 5, 6, and 7 stops with 1.3 and 8 stops being achieved at each end of the filter ring's range of travel (MIN and MAX positions). An additional "X" mark on the filter's ring indicates the density point at which cross polarization (X pattern) begins, slightly, to visually appear when using most wide-angle lenses (a phenomenon common to all VND filters).
As an HGX Prime filter this 55mm variable ND is one of the finest in the world. Its Repellamax II coatings, optical glass, and color-corrected polarizing films (applied using a unique, super-secret, process) combine to provide an extremely sharp image with excellent color rendition as well as protection against moisture, oil, dirt, and dust.