Looks too simple to be useful but this specially beveled glass is ideal for preparing your leather for carving. Used for years by many avid leathercrafters. Simply case your leather normally and then drag the glass across the grain side of the leather. This action will compress the leather grain, thus providing for better cuts and for better uniform coverage of dyes and finishes. Also used by bookbinders to help form and crease their leather.
Can also be used to obtain a subtle shine on grain side of smooth leather, or to smooth rough flesh sides in combination with gum tragacanth.