Made of German Schott optical glass and carefully surface-polished, the multi coats minimize reflection rate to its lowest and preserve accurate color balance and sharp image formation. The filters are raindrop, oil, dirt and scratch proof. ND0.3 (2x) – ND3.0 (1000x) ensures it is hue-error free when shooting. Special frame prevents unwanted light sources from entering the lens like hoods do. It can be used with any wide-angle lens. Density index is shown clearly for accuracy. The filters can be easily and comfortably adjusted and are hue error-free.