Sigma 77mm WR Ceramic Protector
WR Ceramic Protector 50 percent thinner and weighs up to 30 percent less than previous SIGMA filters while offering a higher level of strength! The new SIGMA filter made with Clear Glass Ceramic offers over 10 times the strength of a conventional protective filter and over 3 times the strength of a high-strength protective filter made with chemically hardened glass of the same thickness.