A polarizing filte is often placed in front of the camera lens in photography in order to darken skies, manage reflections, or suppress glare from the surface of lakes or the sea.
Some filters are a single piece of glass that fits into a mattebox. A rotating polarizer also fits into a mattebox but has the function of rotating 360 degrees to counter reflections that may be at particular angles. This allows you to have the camera in the preferred place while managing the reflections of water, windows and other surfaces.
You can rent the set or individual filters. Please contact ProHD for more information and availability.