Visual cues and tactical feel can be deceiving. The fact of the matter is that, out of the box from the factory, there is no difference in the handle slab thicknesses or pivot between this year's Regular, the Classic 2000, and the Classic 21. (I make that "this year's" distinction because Chris is continuously making improvements across the product lines, and I don't want to count out the fact that one of those improvements would be noticed in a comparison between an older Sebenza and a newer Sebenza.) Relative to the Classic 2000, the Sebenza 21 sports a larger chamfer on the pivot end of the knife, a different chamfer around the handle perimeter, and loses the alpha-numeric engraving. That's it.