The HOYA HD Digital UV Filter features 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 & weight were dropped from a height of 50 inches onto the glass. The HOYA HD Digital UV Filter is a multi-purpose fine weather filter, it will absorb the ultra violet rays which often makes outdoor photographs hazy & indistinct, this UV Filter could also be used as a permanent lens protector. Newly developed industry leading 8-layer multi-coating yields an average light transmission rate of 99.35% between 400 & 700nm (visible spectrum).HD Glass- High Density Sharp Cut UV Glass- Chemically Enhanced Optical Glass is 4x Stronger 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