1" ITA lightweight, high quality alloy sealed bearing threadless headset. Lightweight aluminium cupsSealed cartridge 36/45 deg. angular contact bearings.Secure fit to fork with split compression ring.Alloy top cap and std. Star-nut* included (*Caution: Do not use Star-nut in conjunction with Carbon steerer forks.)Â 1" Italian specification sizing: Crown race: 26.4mmHeadtube ID: 30.2mmFork steerer OD: 25.4mmStack Heights: Upper: 14.5mmLower: 11.8mmTotal: 26.3mm