Why you change this rear coil spring kit for your truck? -50% greater carrying capacity and/or added capacity to the tongue weight. Designed keeping towing in mind. -Avoid wearing or sagging coil springs can cause premature tire wear due to vehicle misalignment. -Super high quality can prevent corrosion rust and compressed and long service life. -Easy to install -24 months warranty What’s the difference between the 50% load capacity coilspring and the variable coilspring? -The variable coilspring is a heavy-duty rear coil with a variable rate that sits at stock ride height which can help lift the drooping rear of the car by about 2". This is a good application for trucks that are empty most and then having to carry a heavy load at times. -The 50% load capacity coilspring is an extra heavy-duty rear coil which provide an additional 50% load capacity, or increase the capacity of the bracket weight, at stock height, it can carry an additional 900 lbs. Including: A pair of coil spring Fits: Dodge Ram 1500 2WD and 4WD (2009-2018) If you have an Ram 1500, 2019 and newer model then you might need to buy additional isolators. These isolators are intended for the DT new body style trucks.