Tiffen 52mm Variable Neutral Density Filter 52VND B&H Photo Video
52mm Variable ND - HGX Prime (1.3 - 8 stops)
Amazon.com : K&F Concept 52mm Variable ND Filter ND2-ND32 Camera Lens Filter (1-5 Stops) No X Cross HD Neutral Density Filter with 28 Multi-Layer Coatings Waterproof (Nano-X Series) : Electronics
Platinum™ 52mm, 58mm and 67mm Variable Neutral Density (ND) Lens Filter PT-MC400VND67 - Best Buy
Amazon.com : 52mm ND Variable Neutral Density Filter for Fuji 35mm f/1.4 R Lens : Electronics
K&F Concept 52mm ND Neutral Density Lens Filter Variable Adjustable ND2 to ND400 | eBay