NiSi 58mm HUC IR Neutral Density Filter ND64 (1.8) 6 Stop | NiSi Optics USA
Amazon.com : Breakthrough Photography 58mm X2 6-Stop Fixed ND Filter for Camera Lenses, Neutral Density Professional Photography Filter, MRC8, H-K9L Glass, Nanotec, Ultra-Slim, Weather-Sealed : Electronics
Amazon.com : NiSi 58mm Circular HUC PRO Nano IR ND64 | 6-Stop Neutral Density Camera Lens Filter | Optical Glass, Nano Coating, IR Reduction, Slim Aluminum Frame | Long-Exposure and Landscape Photography : Electronics
Amazon.com : NiSi 100X100mm Square Neutral Density Filter,IR ND64(1.8), ND 6 Stops 100mm System Optical Glass for 52mm,55mm,58mm,62mm,67mm,72mm,77mm,82mm Lens,Compatible with Lee Cokin Hitech Singh-Ray : Electronics