Classic Shimano HP7410 Dura Ace 1 inch threaded headset. Material: aluminium, with sealed cartridge ball bearings. Bearing cup outer diameter: 30.0mm (head tube inner diameter), fork cone / fork crown race inner diameter: 26.4mm, stack height: 37.6mm, weight: approx. 98g, Shimano Item No.: IHP7410B
For installation and adjustment, headset wrenches with 32mm jaw width are required.