Heat Treated Steel Bearing Race Material. Must Machine Cam Sprocket or Engiine Block .030 to Ensure Proper Chain Alignment. Prevents Wear On Engine Block. Can be Used to Repair a Damaged Engine Block Thrust Surface. Product Features:Heat Treated Steel Bearing Race MaterialMust Machine Cam Sprocket or Engine Block .030 to Ensure Proper Chain AlignmentPrevents Wear On Engine BlockCan be Used to Repair a Damaged Engine Block Thrust Surface.