This Standard Isu Bokken is made of quality Isu wood which grows in southern Japan and features a flat spine and flat butt.
This long model is recommended for Aikido and Koryu pracitioner for suburi and general paired contact kata practice. What is Isu? Isu
wood comes from a tree that is officially called "Isu no ki
Isu no Ki produces a exotic hardwood which can be split into Isu and Sunuke wood and can mainly be found south of Kyushu islands.
This wood is characterized by the fine grains and the warm and charming coloration, which ranges from a light creamy color to the dark chocolate color of Sunuke, gives it a feeling of exquisiteness. In terms of hardness it's harder than Oak and could be said to be one of the hardest materials that can be found in Japan.
In the last few years, this material has become more and more rare, especially Sunuke which is extremely heavy and hard, and is mostly used to make high quality Bokken. Since it is both hard and heavy, a lot of practitioners use Bokken made of this material in Japan.