The XB2 ball differential is recommended for all XB2 designs whenever positioned on very-low to medium-traction dust or clay areas to improve traction. The externally-adjustable ball differential is machined from HUDY Spring metal™ and it's also hardened for additional durability and long lifespan. A high-quality carbide thrustbearing and carbide balls are included for ultra-smooth procedure. The ball differential comes factory pre-assembled.