This protective lens filter might look like any other, but it's got an invisible secret. Making use of a new kind of clear ceramic, it's ten times tougher than most conventional protective filters, so is virtually guaranteed to keep yours lens perfectly safe. Developed by Sigma, the clear glass ceramic is made using a special heat treatment technique which creates a nice, even microstructure. With it, that brings some impressive material properties. Like, uh, it's ten times tougher than normal filter glass -- with a Vickers hardness number of 700HV, for material science nerds -- and even three times stronger than a chemically hardened glass filter.
It's also got many of the other features you'd look for in a protective filter: it has high light transmittance (good), and features a coating that helps it repel water, dust and oil. It's available in most popular thread sizes, but is guaranteed to fit any Sigma lens. Also, ten times tougher.
Pricing and availability is not yet available.