A jō (杖:じょう, jō) is an approximately 1.276 m (4.18 foot) long wooden staff, used in some Japanese martial arts. The martial art of wielding the jō is called jōjutsu or jōdō. Also, aiki-jō is a set of techniques in aikido which uses the jō to illustrate aikido's principles with a weapon. The jō staff is shorter than the bō. Today, the jō is still used by some Japanese police forces.