The Hoya HD UV Filter boasts of hardened optical glass that has 4 times the breaking strength in ANSI standardized testing – (ANSI Z80.3 : 2001). This HD UV Fliter also boasts of a specialised coating that is not just waterproof, it also repels water spots and is hardened to be scratch and stain resistant. Of course these coatings are from HOYA so they greatly reduce reflections off the surface of the glass allowing you to capture more light in your photos.