Fabtech smooth ride add-a-leafs. Most add-a-leafs are known for being stiff and hard to install. Well, not anymore. Fabtech has taken modern thin-leaf technology and incorporated it in their smooth ride add-a-leaf kits allowing for an effortless installation and the smoothest possible ride. Add-a-leafs are sold in pairs and include center pins. Long add-a-leafs will need to be inserted within the spring pack in their correct position by length.