Light rays reflected from any surface become polarized, and polarization filters are used to select which light rays enter your camera's lens. PL- (linear polarizing) and PL-CIR- (circular polarizing) filters have the same effect, but it is important to choose the right version for your camera. They allow you to eliminate unwanted reflections from non-metallic surfaces such as water and glass. Additionally, they make colors appear more saturated and clearer, with better contrast. This effect is often used to enhance the contrast and saturation of blue skies and white clouds. HOYA's polarization filters do not affect the overall color balance of a shot.