Light rays which are reflected by any surface can become polarised so polarising filters are used to select which light rays enter your camera lens. CIRCULAR PL filters 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. HOYA's polarising filters do not affect the overall color balance of a shot. Digital multi-coated filters greatly reduce the appearance of lens flare and ghosting caused by reflections. Filters feature a black matte aluminum satin finish almite frame which reduces reflections. These filters are equipped with black rimmed glass to reduce the chance of light reflecting off the edge. Ultra thin filter frames to help avoid vignetting on super wide angle lenses are also designed to hold a lens cap. These filters are equipped with a straight knurling edge for non-slip, easy attachment and removal. Filter cases are UV protected to further lengthen the life of filtersPROP 65 WARNING: This product can expose you to some kind of chemical, which is known to the State of California to cause cancer.