Offering unprecedented protection for your lenses, Sigma's WR Ceramic Protector Filters revolve around a new and unique type of glass—Clear Glass Ceramic. This specialized substrate is claimed to offer 10 times the strength of conventional protective filters and three times the strength of chemically hardened filters, all while measuring up to 50% thinner and 30% lighter in weight than other Sigma filters.
This strength is made possible by a heat-treatment process that precipitates micro crystals of spinel (a type of mineral/gemstone) evenly throughout the entire filter, which leads to uniform, consistent durability that is harder than chemically strengthened glass and more flexible than sapphire crystal glass. The filters are also scratch resistant and shock resistant, and feature a WR (Water-Repellent) coating that deflects moisture and oil from the surface, as well as prevents static electricity from attracting dust. The coating also minimizes ghosting and flare, and allows for 99.76% light transmission for maintained image quality.
WR Ceramic Protector Filters are available in 67, 72, 77, 82, 86, 95, and 105mm sizes, and are delivered with a unique molded acrylic hard case.