34mm for external type (the frame head tube internal diameter size)
28.6mm for front fork beam tubediameter size
Material: aluminum alloy 7075-T6 +Bearing
Structure: Double bearing
semi-concealed, Fully Sealed Bearing
Feature: Anode Process
For Caliber: Upper Inner Diameter: 34mm
Lower Inner Diameter: 34mm
For Front Fork: Standard Straight Pipe upper 28.6mm/lower 30mm
Weight: 105g
Package: 1pc bike headset