These are the HPI Savage Threaded Aluminum Shocks # A712 for all the HPI Savage trucks including the 21, 25, and SS. These are premium, high quality upgrade shocks that come with precision machined aluminum bodies, threaded adjustment for fine tuning spring preload, and protective rubber boots to help keep the shaft shafts cleaner and shock seals lasting longer. Also comes with extra pistons and the necessary shock end hardware. These are very nice shocks for the HPI Savage trucks!