Ikan Nano IR ND 1.8 4x5.65 NiSi Nano Infrared Neutral Density 1.8 Filter - 4 x 5.65 (Black) 6 Stop Infrared Neutral Density Filter 4 mm thick optical glass with precision cut, grinding, and polishing Ultra low color shifting with anti-reflective coating Water proof, scratch, and oil resistant Optimized for shooting raw 6K digital images