Kit includes an easy to install RAS Standard Duty Spring for each rear leaf spring. RoadActive Suspension kits are designed to strengthen the rear leaf springs for towing or hauling without negatively affecting unloaded ride quality. This kit will reduce rear bounce and squat when loaded while significantly improving stability, handling and performance at all times. Select HD kit if your truck has factory TOP overload spring. Estimated install time is 1 hour for truck without factory overload spring.