The Sirui Reverse GND16 – 4 Stop (1.2) Filter- 100x150mm is a Reverse graduated Neutral density filter designed to designed to balance the exposure between the sky and the foreground when the exposure is uneven by 4 stops. The Reverse GND is designed to be used on a flat horizon and is perfect for sunrise and sunset when the brightest part of the scene is on the horizon. The Sirui Reverse GND16 – 4 Stop (1.2) Filter- 100x150mm is 2mm which and 100x150mm and can be used in the Sirui 100mm Filter Holder with CPL or other 100mm holders like NiSi, Lee and Cokin. It’s made from German manufactured Schott Plate Glass B270 with exclusive lens coating process, allows many ultra-thin layers of coating to be placed on each glass surface to insure perfectly linear, uniform reduction of light from edge-to edge, maximum light transmission, reduced reflections and precise color rendition. The GND filter features a Protection Coating (waterproof, oil-resistant, scratch-resistant, anti-reflective, anti-static) for easy cleaning and superior lens protection.