Cutting edge NASCAR CUP series technology for your Shelby or Mustang vintage road racer. These specially designed spacers fit solidly between the inner races of the front wheel bearings. Utilizing special shims they eliminate bearing play that can produce unwanted rotor run out which, in turn, can produce caliper piston kick back and a low brake pedal. For use with Cobra Automotive competition hubs equipped with A12 and A13 bearings, not included. Precision machined from 12L14 steel these are primarily designed for all out competition use. Bare steel finish.