The Heliopan 95mm Kaeseman Linear Polarizing Glass Filter is constructed from select polarizer foils and especially prepared optical glass. Kaeseman ("encased") filters are completely edge-sealed for maximum durability under extreme climatic conditions. Polarizing filters are used to select which light rays enter your camera lens. They can remove unwanted reflections from non-metallic surfaces such as water or glass and also saturate colors providing better contrast.