Color and contrast enhancement. Light rays which are reflected by any surface can become polarised so polarising filters are used to select which light rays enter your camera lens. CIR-PL filters allow you to remove unwanted reflections from non-metallic surfaces such as water, glass etc. They also enable colors to become more saturated and appear clearer with better contrast. This effect is often used to increase the contrast and saturation in blue skies and white clouds. HOYA's polarising filters do not affect the overall color balance of a shot. HD POLARIZING FILM: High Transparency & High Durability UV Absorbing Film. 25% Greater Light Transmission than Standard Polarizing Film. HD COATING: 8-layer Anti-Reflective Multi-Coating. Water & Oil Repellent, Scratch & Stain Resistant. HD FRAME: Wide-Angle Lens Compatible Ultra Thin Frame. Glass Mounted with High Pressure Press Technology