Amazon.com : NEEWER 67mm Variable ND Filter ND8-ND128 Camera Lens Filter (3-7 Stop) No X Cross Neutral Density Ultra-Slim HD Filter with 30 Multi-Layer Nano Coatings Waterproof, Cleaning Cloth Included : Electronics
Amazon.com : Cokin Square Filter Full ND Creative Kit - Includes ND2 (1-Stop), ND4 (2-Stop), ND8 (3-Stop) for L (Z) Series Holder - 100mm X 100mm : Electronics
8-STOP VARIABLE ND FILTER(58mm-82mm) – Official 7Artisans Store
Amazon.com : 52mm ND Filter - 8 Stops of Light ND Adjustable Neutral Density Variable Fader Filter Lens 52mm Variable Neutral Density Filter - 52 mm ND Filter Japan : Electronics
Ice 84 x 98mm P Series ND8 Solid Neutral Density 0.9 ICE-ND8-P
Fotodiox Pro 145mm Ultra Slim Neutral Density 8 (3-Stop) Filter – Fotodiox, Inc. USA