DRP Patented Adjustable Wheel Bearing Spacers, US Patent No. 6,312,162, adjust to set the proper “bearing gap”, the distance between inner and outer bearing. This prevents bearing pre-load, allowing the spindle nut to be completely tightened and bearing load to be distributed across both bearings. DRP Hub Defenders are easy to install and make an immediate difference you can feel. Prevents over tightening. Reduces Drag. Reduces Temperature. Simplifies maintenance.