Interchangeable lenses are crucial for photographic expression and valuable equipment for photographers. Sigma has developed innovative filters for front lenses that meet the company's high-quality standards and allow photographers to utilize the lenses in which they have invested significant time, experience, and money over the years. In creating the new protective filter for lens front elements, Sigma collaborated with a glass manufacturer for the first time to produce a new type of material, clear glass-ceramic. The Sigma WR Ceramic Protector, made from this advanced material, is an extremely reliable filter with outstanding protective properties.

Glass-ceramic is a highly resistant, crystallized glass that forms the basis for clear glass-ceramic and is widely used in aerospace and other industries. This advanced material combines greater hardness than chemically tempered glass with more flexibility than sapphire glass while providing the high light transmission required for optical devices. These properties make clear glass-ceramic the ideal choice for lens protection filters.

Conventional high-strength protective filters use chemically tempered glass, which is only hardened on the surface through chemical processes. In contrast, clear glass-ceramic undergoes a special heat treatment that ensures an even distribution of mineral spinel, resulting in consistent hardness throughout the filter. The combination of greater hardness than chemically tempered glass and greater flexibility than sapphire glass makes clear glass-ceramic the perfect material for protective filters. Additionally, clear glass-ceramic is resistant to small scratches or chips, reducing the risk of fragmentation into small pieces and providing a higher level of safety.