After installation, the tolerance zone of the threaded hole depends on the manufacturing tolerance of the wire thread insert profile and the thread tolerance zone of the mounting hole. The former is controlled by the wire thread insert manufacturer, while the latter mainly depends on the tapping accuracy of the mounting hole, typically forming a 6H grade tolerance zone, which can reach 5H or 4H grades for higher precision. The unified thread standard is 2B or 3B.
The corresponding grade plug gauge can be used to inspect the thread in the pilot hole.