Amazon.com : NiSi 55mm Swift True Color ND-Vario - Variable Neutral Density Filter 1-5 Stops (ND2-ND32) - Rotating Adjustable ND, Compatible with NiSi Swift System Filters - Optical Glass, Waterproof Nano Coating : Electronics
NiSi SWIFT 55mm True Color ND-VARIO Pro Nano 1-5stops Variable ND | NiSi Optics USA
Polaroid Optics 55mm Neutral Density Filter [ND 0.9] Compatible w/ All Popular Camera Lens Models - Walmart.com