Cerax is the best-known brand of the Suehiro company. The stones sold under this name have a medium-hard bond and are particularly suitable for high-alloy tool steels but also for low-alloy carbon steels. The coarse-grained alloy constituents (e.g. chromium and vanadium) in tool steels require a stone that wears slowly. The stone with the base has extra stability and is easy to store. A Nagura stone is used for cleaning and unclogging the surface of the stone and for creating a fine polishing paste. White aluminium oxide abrasive. Before use, soak the stones in water for at least 10 minutes, but do not store them in water permanently.