Are you dialing in the fit of your bike and wan to get everything set before you cut your steerer tube? This is the part for you! This spacer will let you set the headset preload without installing a star nut letting you fine tune everything before cutting the steerer tube. After installing your headset spacers and stem, the Micro-Adjustable spacer snugs up your stem against the spacers with a 36mm headset wrench.