For accurate shaft profiling and frequency matching. Replace the slip clutch with this bolt and tighten your clamp with an inch/lb torque wrench to get precise, repeatable frequency readings. Using a torque wrench enables you to get the most consistent readings possible every time you use your machine. NOTE: Be sure your torque wrench is an inch/lb wrench, not a foot/lb wrench. Most members report 20 – 21 inch/lb settings works for them.