Rent a Tiffen 67mm Variable ND Filter at LensProToGo.com
Cokin 67mm NUANCES Variable ND Filter (5 to 10-Stop) CNV32-67
Syrp 67mm Variable Neutral Density Filter Kit SY0002-0007 B&H
Platinum™ 52mm, 58mm and 67mm Variable Neutral Density (ND) Lens Filter PT-MC400VND67 - Best Buy
Moment Variable ND Filters (600-046) - Moment
Amazon.com : NiSi 67mm Swift True Color ND-Vario | 1-5 Stops Variable Neutral Density Filter | Adjustable ND, True-to-Life Color, No Vignetting, Optical Glass with Nano Coating | Photography and Videography : Electronics