Color and contrast enhancement with the Hoya HD CIR-PL filter. Light rays reflected from any surface can be polarized. Therefore, polarizing filters are used to select which light rays enter your camera lens. With CIR-PL filters, you can eliminate unwanted reflections from non-metallic surfaces like water and glass. They also allow colors to appear more saturated, clearer, and with greater contrast. This effect is often used to enhance contrast and saturation in blue skies and white clouds. Hoya's polarizing filters do not affect the overall color balance of a shot. The filter features a highly transparent and durable UV-absorbing coating that offers 25% higher light transmission than standard polarizing filters. HD coating: 16-layer (both sides) anti-reflective multi-coating, water and oil repellent, scratch and dirt resistant. HD frame: ultra-thin frame compatible with wide-angle lenses, mounted on glass using high-pressure pressing technology.