Can be used on the RIGHT front of open wheel modifieds and street stocks racing on dirt surfaces to reduce right front braking bias to aid in corner entry. Can be used on the rear of open wheel modifieds and street stocks racing on pavement surfaces to reduce rear brake bias. Undersize 2 1/4" piston provides approximately 20% less caliper clamping force for increased brake bias. Increases range of brake bias adjustment for better brake performance. Allows for more brake system tuneability. Assembled with new piston and internal parts. Quality control checked and pressure tested. Stock appearing. 6.4lbs. Mounting Center 5 1/2"