The Cokin 164 Circular Polarizer Glass Filter removes polarised light to improve outdoor images. Circular Polarising filters darken blue skies adding contrast and making white puffy clouds stand out for a more dramatic scene.Light rays reflected from glass or water become polarised. A polarising filter removes unwanted reflections, which increases colour saturation in outdoor photography. It also takes the sheen (reflections) off water to make it easier to see what is beneath the surface. The effect can be seen through the viewfinder and changed by rotating the filter.*NOTE: The Cokin 164 series polarizers will not work with the Cokin EVO filter holders.Specs:- Filter Dimensions: M (P) - 84mm x 84mm x 1.6mm, L (Z) - 100mm x 100mm x 1.6mm, XL (X) - 130mm x 130mm x 3mm- Filter Construction: Optical Glass- Filter : M - P164, L - Z164, XL - X164