Wright heavy duty filled-for-life (sealed), ball bearing spindles are made of ductile iron for greater flexibility and wear, impact and fatigue resistance, providing ongoing cost savings for the fleet operator. Wright medium spindles (Stander B™ only) share the same mounting and bearing as the heavy duty spindles but with aluminum housings, and they are not grease filled. Wright spindles are reliable for many hours and they don't require maintenance – a great fleet feature.