A Jo is a round stick about 50 inches long and 7/8 to 1 inch in diameter. A sapling is ideal because it does not have a directional grain. The grain is circular around the center. In Aikido everyone uses a Jo that is about 50 inches. Because some Shamans teach that a 50 inch stick makes a great antenna for Ki Aikika who believe in Ki use a 50 inch Jo. Uyeshiba O'Sensi was a spear expert and our Jo moves derived from his spear art. It is highly informative to practice Jo techniques with a spear.