Hoya Variable Neutral Density Filter - 58mm — Glazer's Camera
Platinum™ 52mm, 58mm and 67mm Variable Neutral Density (ND) Lens Filter PT-MC400VND67 - Best Buy
Amazon.com : NiSi 58mm 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
Vivitar Series 1 Variable Range Neutral Density Filter 58mm - Video Camera Center