NiSi announces new filter kits for iPhone, including ND, polarizer & more: Digital Photography Review
Amazon.com: Kase 41mm Magnetic Polarizing CPL Filter for iPhone,Cell Phone Camera Lens Circular Polarizer Filter with Clip for iPhone 14 13 12 11 8 7 XR X XS,Samsung Xiaomi OnePlus : Cell Phones & Accessories
Kase 41mm Magnetic CPL Filter for iPhone,Cell Phone Camera Lens Circular Polarizer Filter with Clip for iPhone 13 12 11 8 7 XR X XS,Samsung Xiaomi OnePlus : Amazon.sg: Electronics