Steel Ball

Steel Balls are versatile weapons primarily featured in Part VII: Steel Ball Run, though they have first been seen in Part II: Battle Tendency.

Executions
The basic Steel Ball is primarily used by the executioners serving the royal family of Naples, and is handed down through generations of the Zeppeli family's members. The Steel Ball's techniques were primarily developed in order to give even the worst criminals an honorable death.
 * Known users: Gyro Zeppeli, Gregorio Zeppeli

Wrecking Ball
The Wrecking Ball is primarily used by the imperial guard serving the royal family of Naples. Smaller balls called satellites are attached to the ball that can separate and strike on their own. Even if the satellites do not hit their target, the shockwaves caused by the satellite will induce left-side ataxia, causing the victim to lose all sense of feeling in his or her left side.
 * Known user: Wekapipo

Joseph's Crackers
In Part II, Joseph Joestar makes use of American crackers which he passed the hamon through, though not before covering with the special oil. Once enhanced with hamon, the crackers could spin and retaliate much in the same way the Steel Balls do.

They are a set of crackers, a banned toy from the early 20th Century.