Hoya 62 mm HD Digital Protector Screw in Filter
These HD filters use specially hardened glass that is far more resistant to breakage than other optical glass. Hardened Glass... 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 and weight were dropped from a height of 50 inches onto the glass.