Marumi Fit + Slim Circular Polarizer FilterA circular polarizer is designed to do one thing: remove or control reflections from surfaces like water, glass, paint, leaves, sky, buildings, streets, and the list goes on. When light hits those surfaces they create glare that increases highlights, reduces colour and detail. Almost every scene contains some kind of glare, and a circular polarizing filter will help you control that glare before it reaches your image.