ProMaster 72mm Variable ND - StandardProMaster 72mm Variable ND Standard ProMaster SKU: 9559 Helix SKU: PR9559 OVERVIEW The ProMaster Standard Variable Neutral Density Filter provides light reduction of about 1. 3 to 8. 6 stops. The ND3 to ND400 density creates a darkening of the entire image, allowing you to photograph with a wider aperture or slower shutter speed than normally required. Features high quality glass and precision metal frames.