Amazon.com : NiSi 77mm 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
Tiffen 77mm Graduated 0.6 ND Filter 77CGND6 B&H Photo Video