Nikon "II" circular polarizing filters are specially made with thin ring and can be used with wide-angle lenses and dedicated bayonet hoods.
In general, light reflected from water, glass, or other shiny materials is polarized and adversely affects image definition. Circular polarizing filters reduce or eliminate unwanted reflections and increase the overall contrast of subjects in low-contrast situations
Usually, light from the sky is polarized due to reflections and dispersions in the air. Circular polarizing filters cut these reflections, making the sky blueror intensifying colors.