The Tiffen 77mm Photo Twin Pack consists of a UV Protection filter and Circular Polarizer.

UV Protection Filters
UVHaze (UV) filters are wise initial investments. They help protect your valuable investment from dust, moisture and scratches, which can lead to costly repairs. If desired they can be left on the lens at all times for protection. Haze filters provide additional benefits of correction for Ultraviolet (UV) light which can register on film and videotape as a bluish cast and can obscure distant details. Ultraviolet filters allow you to correct for the UV effect to varying degrees. Haze-1 filters absorb approximately 71 percent of UV.

Circular Polarizers
Light rays which are reflected become polarized. Polarizing filters are used to select which light rays enter your camera lens. They can remove unwanted reflections from non-metallic surfaces such as water or glass and also saturate colors providing better contrast. The effect can be seen through the viewfinder and changed by rotating the filter. The filter factor varies according to how the filter is rotated and its orientation to the sun.

Note! Circular polarizers are specifically designed for use with auto-focus SLR cameras (They will also work on manual systems and video cameras without problems)