The Formatt Hitech Circular Polarizer is made from two layers of high quality optical enhancers. The first layer is a standard high efficiency linear polarisation foil that will create the usual desirable blue sky and reflection cutting effects that polarizers are known for in cinematography. The second layer is a 1/4 Wave Retarder which spins the light in a corkscrew type pattern to avoid cross polarisation on cameras that have 3 CCD design, employ a video tap, or have internal variable ND type effects.Circular Polarizers have little noticeable optical downside versus Linear Polarizer and therefore are recommended for most modern cinematography applications.The Formatt Hitech Linear Polarizer is made from high efficiency polarisation foil that creates blue skies, cuts reflections on windows and water, and is considered one of the best optical effects for outdoor cinematography. The high efficiency nature of this polarizer allows for a significant increase in usability in challenging lighting conditions over other polarizers on the market. Made from Schott B270 optical glass and polished for maximum image quality when used with a matte box.- Makes a Blue Sky Bluer- Enhances Clouds- Eliminates Reflections in Glass, Water- Can Be Used in Combo with Other Filters- Made from CR39 Resin