Each laser cut piece of steel is precision bent 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 truck, our hollow rubber springs adjust automatically to keep the vehicle level at all times. This SES Suspension Upgrade replaces the jounce stop on the frame. Its unique design ensures superb ride quality – loaded or unloaded. (There should be a ½” to 1 ½” gap between rubber spring and frame to ensure unloaded ride quality.) Unlike other auxiliary spring systems, the SES Suspension Upgrade guarantees the best of both worlds. FR1504E replaces the bumpstops on the rear suspension of the 2015-2020 Compatible With Ford F-150 2WD and 4WD pickup truck models. This kit is rated at 6000 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.Timbren Suspension Kits (SES Kits) are designed to enhance the suspension of your vehicle. Easiest to use: Rubber cushions absorb road shocks and automatically adjust to uneven loads or road conditions. Easiest to maintain: There are no airlines or fittings to allow leaks. Simply bolt the kit on and you are set for a lifetime of trouble free suspension. Easiest to install: There are no holes to drill, no airlines to route and SES Kits can be installed in a matter of minutes using basic hand tools. The softer ride quality of todays trucks and the mediocre suspensions found on most trailers can cause excessive trailer sway, instability and suspension settling. Timbrens high performance suspension packages will ensure added safety and peace of mind.