The XB2 ball differential is recommended for all XB2 configurations when used on very-low to medium-traction dirt or clay surfaces to increase traction. The externally-adjustable ball differential is machined from HUDY Spring Steel™ and is additionally hardened for extra durability and long lifespan. A high-quality carbide thrustbearing and carbide balls are included for ultra-smooth operation. The ball differential comes factory pre-assembled.