NiSi 40.5mm ND-VARIO Pro Nano 5-9 Stops Enhanced Variable ND FilterThe NiSi 40. 5mm ND VARIO Pro Nano 5 9 Stops (ND 1. 5 2. 7) Enhanced Variable ND is a variable neutral density filter providing an exposure reduction of 5 to 9 stops. The degree of density is easily controlled by rotating the silver knob. The transition of density occurs smoothly which allows the photographer or videographer to adjust exposure length to the exact amount required for a given scene. Providing a reduction of 5 to 9 stops, this filter