We highly recommend using a stretch gauge when installing rod bolts and other fasteners where it is possible to measure the fastener prior to tightening and after tightening. When the bolt has stretched the specified amount, the correct torque or preload has been applied. We recommend you maintain a chart of all rod bolts and copy down the length of the fastener prior to and after installation. If there is a permanent increase of .001" in length or more or if there is deformation, the fastener should be replaced immediately. ARP offers two highly accurate bolt stretch gauges that read in increments of .0005". Features extra heavy duty springs for consistent reputation. Comes with a heavy duty insulated plastic case for protection. A "must" for any serious engine builder.