Optex 77mm Variable ND FilterThe Optex Variable ND is a good quality filter that lets you dial in between 1 and 8 stops of neutral density ideal for changing lighting conditions. For lenses with a 77mm filter thread. While the filter will screw onto 77mm filter threads, the front of the filter uses a 86mm thread. The filter uses hard stops on either end of the rotation, so you can feel when you reach each extreme. In excellent condition.