Fits on top of the dome style pressure plate of BDL drives with Street Drive clutches. Compatible with dome style pressure plates only. Centrifugal forces push the actuator arms outwards which applies extra pressure to the pressure plate. Supplies a positive engagement and prevents clutch slippage. Not recommended for everyday street use. Note 1: Advised for racing or competition use only. Clutch will be harder to pull and on deceleration you will hear more clutch noise from the actuator arms. Note 2: 518697 Lock-Up Clutch is compatible with 518674 (see photo) closed dome style release discs only. Will not fit the earlier open dome models.