The FSA Headset Star-Nut Driver is a precision tool designed for the safe and accurate installation of star nuts into fork steerer tubes. It ensures proper alignment and depth during insertion which is critical for headset preload and overall bike safety.The driver guide sleeve ensures the star nut is pressed in straight while the radial ring stops the tool at the correct depth to prevent over-insertionDesigned for use with 1" and 1-1/8" fork steerer tubes making it suitable for a wide range of headset installations