Rear wheel axle for large ball-bearings made from world-renowned HUDY Spring Steel. Strategically machined for toughness and light weight without compromising strength. The wheel axle is additionally hand ground for maximum precision to ensure a perfect, precise fit in suspension ball-bearings, guaranteeing perfect wobble-free fit and rotation. Heat treated for maximum strength, durability, minimal wear, and extra-long lifespan. Fits only multi-adjustable rear upright #323355.