Pure Harmonie Circular Polarizer filters are the thinnest and the lightest in the world. With a thickness of only 4.5mm they are almost invisible when mounted on your lens. Their weight is so light that you won"t even notice that they are attached. Circular Polarizer filters are used to reduce reflections from non-metallic surfaces such as windows, and water, and help to increase density within the sky and/or foliage by absorbing reflected light. They also help to emphasize details within clouds and produces crisper images, with deeper color tones. This effect cannot be fully achieved with computer software. PURE Harmonie Circular Polarizers have been engineered with no compromise: robust and scratch resistant, compatible with all lens caps, and multi-coated with EVERCLEAR 5 Coating Technology to withstand almost any conditions. Their transmission is among the best in its category in comparison to others due to their thin design, exceptional multi-coating, and special formulated optical glass. These filters only have a 1 stop filter factor which is among the best in its category due to the impressive transmission characteristics of this optical formulation. They are just perfect. They are PURE.