This SES Suspension Upgrade fits the rear suspension of a Toyota Tundra. Each laser cut piece of steel is welded and powder-coated to ensure a quality fit. We've engineered our hollow rubber springs to deliver a progressive spring rate. In other words, the more weight that pushes down on the rubber springs the harder they work to prevent rear end sag. Whether you're pulling a trailer or carrying a heavy load in the bed of your vehicle, our hollow rubber springs adjust automatically to keep the vehicle level at all times.