Slim circular polarizing filter from Hoya for lenses with 67mm filter threads. Part of Hoya's UX line. Light rays which are reflected by any surface become polarised and polarising filters are used to select which light rays enter your camara lens. They allow you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. They also enable colors to become more saturated and appear clearer, with better contrast. This effect is often used to increase the contrast and saturation in blue skies and white clouds.