Light rays which are reflected by any surface become polarised and polarising filters are used to select which light rays enter your camara lens. They allow you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. They also saturate colors and increase contrast. Polarizers come in two variations but have the same effect. Linear polarizers work with older camera meters; Circurlar polarizers are designed for today's newer split-beam metering systems used in auto focus cameras. Check your camera's manual. Hardened Glass: Hardened optical glass that has 4 times the breaking strength in ANSI standardized testing (ANSI Z80.3 : 2001) where a steel balls of varying size and weight were dropped from a height of 50 inches onto the glass. High Transparency Polarizing Film; The polarizing film is the same as that used in the latest high definition LCD TV screens. It has 25% higher light transmission than standard polarizing film used in current photographic filters. Hardened 8 Layer Waterproof Multi-Coating That is Scratch & Stain Resistant: Newly developed industry leading 8-layer multi-coating yields an average light transmission rate of 99.35% between 400 and 700nm (visible spectrum). These coatings greatly reduce reflections off the surface of the glass allowing you tocapture more light in your photos.