This is a ruler primarily used to check the flatness of the bottom of a plane. No nails are used. It's made of wood, so it won't damage the blade even if you touch it. It's used for adjusting the plane bed to improve its accuracy. Made from straight-grained Hinoki cypress. With a brand. It hasn't been used for a long time, so please flatten it before use. #Plane #HandTools #FingerJointing #BottomRuler #BedAdjustment #Jig