MAVIC 2 PRO Graduated ND Filter Set | PgyTech are intended to be used when the horizon is in view. The air is usually 2-3 stops lighter than the ground, so you have a heavier ND filter at the top of your image than at the bottom. This set consists of 3 gray gradient filters, an ND8-GR (3-0 stops), ND16-4 (4-2 stops) and an ND32-8 (5-3 stops) filter. The ND8-GR filter is best used during the 'golden hour'. This filter corrects from 3f-Stops to 0-Stop. On a cloudy day there is the ND16-4 filter, with an exposure correction from 4-Stops to 2-Stops. On sunny days you can use the ND32-8 filter, which corrects the light from 5 f-stops to 3 f-stops. The filters are made of high quality German SCHOTT glass with multiple layers of coating on both sides. The coating ensures that fewer reflections are visible, and the image is brighter. In addition, the coating makes the filter water-resistant, grease and dust-resistant and scratch-resistant. The SCHOTT glass is polished, for even better image quality. The glass and the coating together ensure a high-quality filter that lasts for a long time and is easy to keep clean.