Stepped liner bushings are used with flush mount SpeedLoc locators and offer a flush work surface free from interference (stepped liners may be used with standard SpeedLoc locators). Liners protect the integrity of locating holes on bases, fixture plates, indexers and other workholding devices. They are a critical component for creating the highest possible machining accuracy and extending the life of the SpeedLoc System. For most applications, only two bushings should be used to avoid binding and alignment issues. Made from AISI-1144 alloy steel. Hardened to Rc 62-64.