Promaster Variable ND Filter Digital HGX 49mm | Bedfords.com
Filters in Photography: A Complete Guide to ND Filters
Moment Variable ND Filters (600-046) - Moment
Best variable ND filter - Camera Jabber
Create Your Own Variable Neutral Density Filter
Amazon.com : K&F Concept 62mm 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
Tiffen 72mm Variable Neutral Density Filter 72VND B&H Photo Video
SLR Magic Cine II 50mm f/1.1 Lens & Variable ND Filter Kit (Sony