Characterized by its uniquely durable construction, the 77mm WR Ceramic Protector Filter from Sigma is a clear filter designed to guard the front of a lens from impacts, scratching, and other elements. Developed using a clear glass ceramic substrate, this filter blends a high 99.76% transmittance value with greater hardness than chemically-strengthened glass and greater flexibility than sapphire crystal glass. This results in a build that is shock- and scratch-resistant to withstand a variety of impacts while shooting. Additionally, a water-repellent coating has also been applied to resist water droplets and fingerprint smudging, as well as static electricity from attracting dust or other particles. Built for use in trying conditions, the unique design of the WR Ceramic Protector Filter helps to maintain the lens' inherent image quality while affording a high degree of protection.