SR Add-a-Leafs = Softride Add-a-Leafs, for fatigued stock springs.
HD Add-a-Leafs = Heavy Duty Add-a-Leafs, for extra payload capacity.
If you plan to mount a winch, install heavier bumpers, or do a lot of towing and hauling, you may want to consider installing Add-A-Leafs on your vehicle...
Add-A-Leafs will increase your payload capacity by 250 lbs to 500 lbs and give you additional height. If your stock springs are sagging you may want to use an Add-A-Leaf to bring your truck back up until you can afford replacement springs. These Add-A-Leafs can be easily installed with a good set of basic hand tools-without removing the stock springs. (Note: All Add-A-Leaf's are sold as kits and include 2 Add-A-Leafs and longer Center Pin Bolts.)