The NIP-70-RGND0.9 is a graded filter for 70mm photo filter systems. This filter has a reverse grade, which means the tint darkens in the center of the glass, then fades back to clear again at the top. In this case, that tint changes goes from clear (0-Stop) to a 0.9 (3-Stop), then back to clear. The NIP-70-RGND0.9 has a standard thickness for a photo filter (2mm) and will work in any photo-standard filter system.