Wobble ball

Wobble balls were used in the training of Jedi. Repulsors could levitate them off the floor, and during a sparring match a Jedi could use the Force to pluck it out of the air, and hurl it at someone. This would teach a Jedi to be more focused, and to avoid distractions during combat. A wobble ball was heavy enough to knock a grown man down when thrown with the Force. Wobble balls were able to be cut in half with a lightsaber.

Luke Skywalker used some wobble balls in the New Jedi Temple's sparring arena against his son, Ben, when he was trying to see how well Jacen Solo was teaching him to defend himself.

Text and facts from the “Wobble ball” article on Wookieepedia, licensed under CC BY-SA 3.0. Modified for this site.