This is a SIGMA WR CERAMIC PROTECTOR 82MM. I'm selling it because I haven't been using it much. As you can see in the photos, the knurling is slightly worn. Please be aware of this beforehand. I've heard about potential product swaps, so I'm sorry, but returns are not accepted. Also, please excuse any scratches on the lens case. The following is an excerpt from the product description: The world's first* filter using glass ceramics has arrived. It's the birth of a "true protector" that can protect your precious lenses. Interchangeable lenses are the most important element in photographic expression. As a key device for creating images, they should be the most important asset for the photographer. What can Sigma do to help you use your valuable interchangeable lenses for a long time and with care? From that perspective, Sigma believed that "protective filters" should also be developed and realized based on our own standards. In filter development, from an unprecedented collaborative relationship with a glass material manufacturer, a "true protector" made of a completely new material was born. The Sigma WR* CERAMIC PROTECTOR is a highly reliable protective filter that uses "clear glass ceramics." Clear glass ceramics uses high-strength glass ceramics (crystallized glass), which is also used in the aerospace industry, and is a new material that achieves the transmittance required for optical equipment. It has ideal properties for protective filters, such as higher hardness than conventional chemically strengthened glass and greater flexibility than sapphire crystal glass. *WR: Water Repellent