ATHABASCA ARK II 170 x 190mm GND32 (1.5) Square Filter Athabasca ARK GND filters are made of German Schott B270 optical glass. The use of Schott optical glass gives our square filters excellent properties of chemical resistance, high temperature resistance, and abrasion resistance. With an ultra-thin noble metal multi-coating, Athabasca square filters are with low reflection and able to avoid color differences while also being water, stain and scratch resistant. GND (Graduated Neutral Density) filters are half neutral density and half clear. As the limited latitude of digital cameras cannot allow for shooting environments with strong light/dark ratios, GND filters are often used to balance the light contrast between strong and weak light. MaterialGerman Schott B270 Optical Glass Coating: Water repellent, Stain and scratch resistant Double-side anti-reflective coating Size: 170*190*2mm