Cane Creek's 10 Series has light, tough, and beautiful machined 6061 T6-aluminum cups, Cane Creek's corrosion-resistant black-oxide angular-contact bearings and quality seals throughout to keep the grease in and the dirt out. - Technical Description: EC34/28.6/H16/K|EC34/30 /H12/K - Top Type: EC - External Cup - Top Head Tube Inside Dia.: 33.95mm - Stem Clamp Dia.: 28.6mm - Top Stack Height: 16mm - Top Bearing Type: Black Oxide - Bottom Type: EC - External Cup - Bottom Head Tube Inside Dia.: 33.95mm - Crown Race Seat Dia.: 30.015mm - Crown Race Type: Polymer - Bottom Stack Height: 12mm - Bottom Bearing Type: Black Oxide - Material: 6061 aluminum - Weight: 88.29g