These premium bushings are made from a synthetic elastomer that provides very similar handling performance and longevity when compared to polyurethane but without the squeaking. This modern material is firmer than OEM rubber but has a slightly softer durometer than traditional polyurethane which will improve overall ride quality by eliminating some of the harshness associated with polyurethane. A great balance that allows you to get comfort and performance at the same time. Concours correct washers and unique 9/16" x 18 locking nuts are included.