The Kubotan is a genericized trademark for a self defense weapon developed by Takayuki Kubota in the 1960s. The principal targets in self-defence include bony, fleshy and sensitive parts such as knuckles, forearms, the wrist, shins, solar plexus, ribs, etc.  Common uses include hardening the fist (fistload) for punching, attacking vulnerable parts of an assailant's body, and gaining leverage on an assailant's wrist.  My version of the Kubotan is 6 3/4" long and .90" in diameter with a different finish on each end for varied strikes.  All are made out of beautiful pieces of the same species of woods as my batons.