Featuring its patented bolt on design, Silent Ride polyurethane stability blocks, plated and powder coated components and easy to follow installation instructions make this the helper spring of choice for do-it-yourself and professionals alike. Manufactured with heat treated ASTM 5150 alloy spring steel, these units increase your vehicles level load carrying capacity up to the manufacturers Gross Vehicle Weight Rating. With its progressive rate design this helper spring system enables trucks and vans to carry loads with more control and stability. As your load increases this spring automatically increases its rate to resist sagging and tail dragging. Packaged in one box which includes all the heavy duty hardware and installation instructions, this unit can be installed in a professional shop or in your own drive way. Simple installation using common hand tools make the Pro Series helper spring a popular and easy to use accessory to assist in all your Tow and Haul needs. Fine tune your vehicles leaf spring suspension to suit your particular needs by adjusting the heavy duty u-bolts provided. If your tow and haul needs change, simply adjust the heavy duty u-bolts to suit the new requirement. Once installed and adjusted you are free to haul and/or tow a multitude of equipment and commodities with greater control and stability.