Superlift Add-a-leafs are a great choice when only 1-2 inches of lift is desired. Also, rear add-a-leafs can be used to beef-up the factory rear springs. Spring fatigue is a common issue among older vehicles or vehicles that have been used frequently for heavy hauling or towing. All kits include 2 single leafs and new tie-bolts. Superlift Add-a-leafs are designed to be used with stock leaf springs only.