Polarizers are essential filters for increasing the image quality of your outdoor photographs because they remove atmospheric haze, increasing contrast between clouds and sky. Polarizers also remove unwanted reflections from water, windshields, windows, and foliage. The anti-reflective properties of fire crest multicasting means your images will have the highest contrast and fidelity. This 77 mm filter features the 7.5 mm thin super slim Ring which is stackable and accepts a lens cap. Note: If you have a autofocus camera or a digital camera with a CMOS chip, you need a circular polarizer, rather than a linear. "Circular" and "Linear" refer to the polarization of the light, not the shape of the filter. (I). E. We make square circular polarizers)