Replacement T-Spring for nodels KJ-XR3 and KJarmstrong XR. It is also compatible with: KJ Pro series (as a softer T-Spring option) older XR series models This T-Spring model features: the new 4 TwinTurbos System (improve balance & rebound) the new SRS (Safety Release System). Customizing option: It is “Coil Spring Adapted” which means that you can attach the optional steel Coil Springs, to customize the compression resistance of your KJ. COLORS: Orange, Yellow, Gray, Pink, Blue