This is the silent style spring bushing that is used on 1957-1975 models. The bushing is steel with a rubber insert in it. On CJ3B models 8 are Required on the shackles only. CJ5, CJ6 models 12 are Required for every spring eye hole. And Truck, Wagon and Delivery models 4 are Required only for the front shackles. Note: The bushings are not required for the silent shackle sets because they are included (Only needed for the pivot eye where required).