This polarizing filter is used to increase color saturation, darken blue skies so white clouds stand out, and eliminate reflections from nonmetallic surfaces like glass or water.
It will also reduce the softness in scenery caused by atmospheric haze.
This filter will not change the overall color balance of a photograph. Most modern SLR camera use a polarizing half mirror (split beam metering) system and the Circular PL is designed to be used with them.