I worked almost all of this rainy day on a project with many dovetails, and the resultant need for several intermittent sharpening sessions. I have been using the MkII narrow blade head since it became available a couple of weeks ago. I know this product was beta tested. Good thing it wasn't me that did that testing, because I have to report very mixed results. I most likely will return the product. The problem is similar to the broader issue of this guide system not holding work pieces well. I suggest that the powder coating is much to blame for this. I have sharpened many chisels with it. So far, I would say that, ironically, my Lie-Nielsen chisels fit into the clamping system the best. I have two chisel sets that do not hold in the clamping jaws: The modern Stanley Sweetheart bench chisels, and the Irwin (Marples) blue-handled bench chisels. These two brands have similar profiles. The sides are mildly beveled but the bevels intersect flat sides that are rather blunt. On this profile the smooth jaws of the Narrow Blade Holder simply don't gain a secure enough purchase to hold the chisel firmly. The jaws have no texture and are covered with the thick powder-coat finish. I also think they are much too small for the job they are required to do. After a frustrating hour of trying, I pulled out my eclipse clone and re-honed my spent chisel edges. I guess I am at the point where I have to decide if the $48. investment is justifiable for such limited utility.