SIGMA WR LENS FILTERS

10 times the strength of a conventional protective filter, 3 times the strength of a chemically hardened glass filter

Made with a special process that evenly precipitates microcrystalline spinel throughout the material, Clear Glass Ceramic offers a Vickers hardness number of 700HV. 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.