Rear wheel axle for big ball-bearings produced from world-renowned HUDY Spring Steel. Strategically machined for toughness and light-weight without compromising energy. The wheel axle is likewise hand ground for maximum accuracy to make sure an ideal, precise fit in suspension ball-bearings, guaranteeing perfect wobble-free fit and rotation. Heat addressed for optimum strength, durability, minimal wear, and extra-long lifespan. Fits only multi-adjustable rear upright #323355.