Amazon.com : PolarPro - Circular Polarizer and Neutral Density Lens Filters for DJI Phantom 3 and Phantom 4 (3-Count) : Electronics
Used Polar Pro Cinema Series Exposure Collection 3-Filter Pack for DJI Phantom 4 Pro Quadcopter / Advanced Camera Drone, Includes ND64 Filter, ND128 Filter and ND256 Filter P4PRO-CS-EXP
PolarPro® Cinema Series ND Filters – Skydio
Amazon.com : PolarPro - Circular Polarizer and Neutral Density Lens Filters for DJI Phantom 3 and Phantom 4 (3-Count) : Electronics
ND Filters for the Phantom 4 Pro - PolarPro - YouTube
Polar Pro Filter 6-Pack for Phantom 3/4
In Depth: Polar Pro Filter Kits for DJI Phantom 4 / Phantom 3 / Inspire 1 - YouTube