Benro Universal Lens Filter Reverse-edged Graduated ND Filter GND8 (0.9) 3-stop 150x170 (UNGND8R1517) High-end PMMA resin material has superior strength and shock resistance With HD optical technology, the precisely grinded surfaces delivers exceptionally sharp, clear images Unlike typical resins, these filters were specially engineered to minimize color shift The WMC coating features the latest anti-scratch technology and provides a water and oil proof surface Scientifically improved graduation has more usable area for superior performance