Promaster 49mm Circular Polarizer Light rays which are reflected by any surface become polarized and polarizing filters are used to select which light rays enter your camara lens. The Circular Polarizing filter allows you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. It also will 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. The PROMASTER Polarizing filter does not affect the overall color balance of a shot. Great for use with all traditional and digital cameras.