Park Tool TNS-4 Deluxe Threadless Nut Setter
The TNS-4 makes it quick and easy to install star-fangled nuts used with 1” and 1-1/8” threadless headset systems. Using a durable steel driver and built-in guide, the TNS-4 perfectly aligns the star-fangled nut and sets it to the proper depth every time. The unique design virtually eliminates pinched fingers.
If you've ever set a star-fangled nut without a guided driver, then you know it can be a pretty frustrating experience. I would also argue that all that sideways action that you run into without the guide would lead to a less secure star nut. The guide works perfectly and makes installation a snap.