The NIP-70-HGND0.9 is a graded filter for 70mm photo filter systems. This filter has a hard grade, which means the tint changes very quickly and suddenly in the center of the glass. In this case, that tint changes goes from clear (0-Stop) to a 0.9 (3-Stop) tint. The NIP-70-HGND0.9 has a standard thickness for a photo filter (2mm) and will work in any photo-standard filter system.