This 754.2 is a reamer for the HTR, which is sized to 33.9mm. It allows a 0.1mm interference fit when pressing the 34.0mm headset of the 1/8" standard.
NOTE: Always use cutting fluid such as Park Tool CF-2 when machining.
SHIS terminology: This tool is used on EC34 upper or lower headtubes
Manufacturer's Part Number: 754.2