These brackets have been designed to allow you to install both, factory seat belts and aftermarket harnesses at the same time. Intended for the use of quick disconnect lap belts on both sides of the seat. This is a perfect set up for your street/track car. This bracket is designed to attach to the factory seat belt mounting locations so no drilling is required. Additional hardware {7/16″ – 20 hex nut} might required to complete the installation.