The RAS? RoadActive Suspension HD rear leaf spring upgrade is the only suspension upgrade that improves towing and hauling performance without stiffening your unloaded ride. Unlike traditional add-ons RAS works with and strengthens factory leaf springs by 40-50% eliminating squat reducing bounce and increasing stability for better driver control. This mechanically active system works instantly to support your truck?s suspension maintaining proper leaf spring arch while absorbing and dissipating load force energy. No adjustments no maintenance?just install and enjoy a smoother more stable ride. Heavy-duty and ideal for towing and hauling RAS? is the only system that guarantees 100% ride comfort and performance loaded or unloaded.