The tonfa is derived from the handles of a millstone. Once again it is probable that farmers made fighting weapons that resembled true millstone handles to such a degree that they were undetected throughout the era of weapon prohibition. The wooden handles were held, while the long shaft was swung and flailed at the attacker, then brought along the forearm to block attacks. The techniques were used in the same manner as Okinawate. For uke (blocking) the shafts of the tonfa were used along the arms; tsuki (punching) made use of the tonfa end; while uchi (striking) used the hinging action of the tonfa in the same way as that of hiji uchi or empi uchi of the empty-hand techniques.
-Michael Finn, Martial Arts: A Complete Illustrated History, The Overlook Press, 1988
Although the tonfa is not a well-known weapon among martial artists themselves, it is actually by far the most often used of the Okinawan weapons. The PR-24 police baton, a direct descendant of the tonfa, is standard issue in police departments around the United States. It has replaced the venerable nightstick because of its effectiveness and versatility in stopping opponents
The Okinawan Karate Club of Dallas teaches Tsun Kwa Tonfa as taught to us by Christensen Sensei.