Leica + Filters (Best filters I use for Leica cameras)
Digital Lens FX – CREATOR FX
Red channel graduated ND filter use – Tom Bol Photography, LLC
B+W 52mm Dark Red SC 091 Filter 65-072087 B&H Photo Video
Amazon.com: PULUZ 32mm Red Filter Diving Housing Red Color Lens Filter for iPhone 8, iPhone 8 Plus Huawei P20, Galaxy S9 and More : Cell Phones & Accessories
67mm Circular Polarizer Camera Red Filter Color Light Remedy Underwater Diving Lens Conversion With Thread Mount - Camera Filters - AliExpress
Infrared 100: Filtering a full-spectrum camera
KASE 77 and 82mm infrared camera filters - Geeky Gadgets