Amazon.com : Polaroid Optics 72mm Neutral Density Filter [ND 0.9] Compatible w/ All Popular Camera Lens Models : Camera Lens Neutral Density Filters : Electronics
Polaroid Optics 52mm Neutral Density Camera Filter ND 0.9 - PLFILND952 815361011219 | eBay
Antares 2" Neutral Density Filter ND-0.9 13% Transmission