This is a rare 2004 Buck 110 folding hunter with experimental carbide "nano" steel. Part of a small run done to test a new type of blade coating that would possibly increase edge retention. In 2004 Buck's engineers were looking at this process, referred to as Nano Steel, and they prepared 4 models for testing. The carbide coating covers the bottom 1/4" down length of the back side of the blade. The blade was sharpened only on the uncoated side of the blade. This process is very similar to the Ion Fusion (aka Buck Coat) used for several years by Buck Knives . After testing was completed and evaluated, Buck determined that it was not a good fit, so Nano Steel was never put into production.