Cokin p series p171 varicolour redblue filter
Light rays which are reflected become polarized 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 if you combine a variocolor with a neutral polarizer you can vary the intensity by rotating the neutral polarizer for example depending on the relative rotation of the variocolor redblue filter and the neutral polarizer the refl