The HOYA HD series of filters offers chemically enhanced optical glass that is said to be 4x stronger than normal filter glass, using ultra clear high transparency optical glass, with an 8-layer anti-reflective multi-coating, that is water and oil repellent, as well as scratch and stain resistant. The frame is wide-angle lens compatible thanks to an ultra-thin frame, and the glass is mounted with high-pressure press technology for a wide opening - something which cheaper filters can cause problems with. 

Main features

• High Density Sharp Cut UV Glass
• Chemically Enhanced Optical Glass is 4x Stronger
• 8-layer Anti-Reflective Multi-Coating
• Water & Oil Repellent, Scratch & Stain Resistant
• Wide-Angle Lens Compatible Ultra Thin Frame
• Glass Mounted with High Pressure Press Technology
• Absorbs the ultraviolet rays which often makes outdoor photographs hazy and indistinct. A multi-purpose, fine-weather filter for color as well as black and white films. Also serves as a permanent lens protector.