I recently rediscovered a hone similar yours. I got the hone in Germany in 1972 while in the US Army. I used it to sharpen knives and about 4 years ago when I started my straight razor adventure I could not find it. About 2 weeks ago I found it. It measures 12x2x1. I remember reading on a label or box that it was German and to use water only. With water only it feels like there is oil on the stone. It is a remarkable finisher. Very fine edges with no microchipping. I have been touching up all of my razors since rediscovering it.