Amazon.com : Haida 2 in 1 CPL + VND Filter for Camera Pro II Multi-Coating Circular Polarizer + Variable Neutral Density SLR Camera Lens Filter Waterproof Scratch Resistant Nano-Coating Filter 82mm : Electronics
Amazon.com : JJC 2-in-1 67mm Variable ND Filter & CPL Polarizer Filter, 5 Hard Stops ND2-ND32 Adjustable Neutral Density Filter, Including Moistureproof Storage Case and Lens Cap : Electronics
Variable Neutral Density Filter for 6.6x6.6" Matte Boxes
Round Continuously Variable Metallic Neutral Density Filters