A few years ago I broke the filter on my 24-70 2.8 Nikon lens. I felt quite the lucky guy, as that lens is about $1,800. The comments on the usefulness of that filter were mixed. I think the comments on how the new Sigma filter protects a lens will be different.
On December Sigma announced that they are developing a new ceramic glass filter that will be stronger than any other filter you know.
Sigma released a video that was very slick (we will link it below) but did not show much of the action. Now Sigma released another movie showing how a 49 gram metal ball is dropped from 127 centimeters onto the filter and the filter survives. (None of the other branded filters do… ). Why 127 centimeters, and why 49 grams? I don’t know. Maybe it those symbolize the first and last names of Sigma founders.