Super-smooth steering, quality materials, cutting-edge design, and serious durability are all hallmarks of Cane Creek's 40-Series headsets. Specifications Technical Description: IS42/28.6/H9/K|IS52/40/H1 Top Type: IS - Integrated Top Head Tube Inside Dia.: 42.00mm Stem Clamp Dia.: 28.6mm Top Stack Height: 9mm (Short), 15mm (Tall) Top Bearing Type: Black Oxide, Sealed Bottom Type: IS - Integrated Bottom Head Tube Inside Dia.: 52.1mm Crown Race Seat Dia.: 39.79mm Crown Race Type: Steel, Face-Sealed Bottom Stack Height: 1mm Bottom Bearing Type: Black Oxide, Sealed Material: 6061 aluminum Weight: 84g