Polar Pro Phantom 4 Pro Filter 3-Pack - Filter kit - neutral density - 25.4 mm - for DJI Phantom 4 Pro - Walmart.com
Best Buy: PolarPro Circular Polarizer and Neutral Density Lens Filters for DJI Phantom 3 and Phantom 4 (3-Count) P8001
Lens Filters for DJI Phantom 4 Pro V2.0 Advanced UV CPL ND4 ND8 ND16 HD Filter Camera Polarizing Neutral Density Accessories|Drone Filter| - AliExpress