The ACT Street Discs are made to exceed OEM Specifications allowing your clutch to hold more torque and last longer. This is a direct replacement piece for the disc that is included with the ACT clutch kit. This provides people who have already purchased an ACT clutch kit to cheaply replace the friction material when it wears out. Remember clutches are just like brake pads; they are designed to wear out over time. Replacement for ACT part numbers SB3-HDSS SB5-HDSS