This SES Suspension Upgrade fits the rear suspension of a Toyota Tundra with a truck camper. 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. More Safety: When extra weight makes your vehicle squat in the back, the front-end lifts up reducing traction on the front tires. Not only that, if the front is too high your headlights will shine up into the eyes of oncoming traffic instead of pointing down on the road ahead. Timbren SES upgrades are designed to keep your vehicle level at all times. This will increase traction on the front tires, improve overall steering and keep your headlights pointing down on the road where they belong. More Stability: If extra weight makes your vehicle top-heavy, you're going to experience body roll and sway. There's nothing more challenging than trying to keep your vehicle moving on a straight path when the load is unstable. Timbren SES upgrades offer you more stability and peace of mind by eliminating suspension sag and reducing body roll & sway. More Comfort: Too much weight can cause your vehicle to bottom out if you're driving over roads that are bumpy and rough. All this road shock will compromise an otherwise comfortable ride. Improve your ride quality by installing Timbren SES upgrades, guaranteed to provide a softer, smoother ride, empty or loaded.