Zomei Ultra Slim HD 18 Layer Super Multi-Coated SCHOTT Glass PRO Fader Variable Density Neutral Gray 72mm ND X Lens Filter Ultra Slim Filter Frame: Zomei HD ND filter is used ultra slim frame, which is suitable for wide and telephoto end, it avoids the dark corners phenomenon. This HD ultra slim ND meets the ROHS requirement, there is no toxic substance. Also, screw thread frame is used by this filter too, lens and accessories can be installed at any time Germany Schott Glass: Zomei ND filters used Germany SCHOTT B270 high grade glass material, which meets for optical lens strict request, it promises excellent luminousness, and also can restore the image quality very excellently. There is no distortion Superior aviation aluminum material: Zomei ND filters frame is used the highest grade aviation aluminum material, which is anti-corrosion and very light (50% lighter than titanium material ), at the same time, it has strong flexibility and super high stability. Black Matte face frame: The frame also use environmental protection artwork and super thin matte face dull polish treatment. Which can maximum avoid parasitic light comes in, thoroughly eliminate the reflect light from nonmetal, put an end to the ray of lights disturb of long time exposure, it makes a very good achtung duo effect. Germany High grade mat paint: Zomei ND filters edge glass are used Germanys high grade mat paint treatment, which avoid stray light and refract light come in, takes perfect image effect