Light rays which are reflected by any surfbecome polarized and Polarizing filters are used to select which light rays enter your camera 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. Polarizers do not affect the overall color balance of a shot. It is important that you choose the correct version of polarizer for your camera. Many of todays cameras use semi-silvered mirrors or prisms to split the light entering the viewfinder in order to calculate exposure and focusing distance. Polarizing filters can sometimes interact with these items to give unpredictable exposure or focusing. Model # 2837 Features: 77mm Diameter Polarizing Material Allows you to remove unwanted reflections from non-metallic surfaces Enables colors to become more saturated and appear clearer, with better contrast.