The Sirui wide angle circular polarizer cpl filter is the perfect addition to the Sirui 18-wa wide angle mobile phone lens. It can help you to achieve excellent results by reducing reflections (on non-metallic surfaces) and enhancing colors during photo or video shooting. High quality German-produced schott glass multi-layer Nano-coatings prevent reflections and ensure high light transmission, neutral color, reproduction - reduces uv radiation what is the Sirui 18-wa-cpl? The 18-wa-cpl is a polarizing filter, a useful addition to the 18-wa wide angle lens. In particular, your landscape shots will become more dramatic and detailed. What can the Sirui 18-wa-cpl do? The polarizing filter provides you with unbeatably strong colors, especially for landscape photos. The sky becomes a dramatic blue, the green of plants becomes bright and detailed. Another great feature of the polarizing filter is that it reduces or blocks reflections from non-metallic surfaces such as glass or water. Looking through a shop window or into a lake is now possible and offers an entirely new perspective for your photos. How do I use the Sirui 18-wa-cpl? The filter is attached to the Sirui 18-wa wide angle lens.