Zykkor Pro Slim CPL Circular Polarizer Glass Filter, 77mm Pro Slim High Quality Optical Glass CPL Filter Reduces glare in water and reflective surfaces, great for foliage in making leaves less shiny Enhances Colors, Darken Blue Skies turning them into deep rich blues Protects your camera lens from dust, moisture, scratches and fingerprints Double threaded to stack additional filters such as: ND, UV, etc.