This SES Suspension Enhancement System Upgrade fits the front suspension of a Chevrolet Silverado 1500 and GMC Sierra 1500 pickup truck. Timbren has engineered hollow rubber springs to deliver a progressive spring rate. In other words, the more weight that pushes down on the rubber springs (weight from a snowplow or heavy aftermarket accessories - such as a steel bumper) the harder they work to prevent front-end sag. This kit is rated at 14000 lbs capacity. Even though you're increasing the spring rate by adding this upgrade, this does not increase the GVWR (Gross Vehicle Weight Rating). Please make sure that the load does not exceed the GVWR set by the manufacturer.