K&F Concept 72mm Fader ND Lens Filter Variable ND2 to ND32 for Camera no x Spot | eBay
Neutral-density filter - Wikipedia
Amazon.com : K&F Concept 55mm 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
Before and After ND | Photography filters, Photography software, Photography techniques
UV vs CPL vs ND Filters Explained: Do you Really need them? — free wild souls