The Carl ZEISS T* Circular Polarizer Filter from ZEISS helps to reduce reflections and glare by filtering out light that has become polarized due to reflection from a non-metallic surface. A polarizer is able to absorb much of this polarized light and, in turn, increase the saturation of skies and foliage, cut through distant haze, and minimize reflections in glass and on water.
A circular polarizer differs from a linear polarizer in that it integrates a quarter wave plane within a linear polarizing filter. The addition of this helps to circularly polarize reflected light, which enables your camera's autofocus and auto-exposure mechanisms to function properly.
The T* anti-reflective coating helps to reduce reflections on the filter's surface and promote a better light transmission for high quality imagery. The filter ring is designed with a slim profile to allow its use on wide angle lenses, but front filter threads are still available for the use of additional filters.