The Speedline Sealed Bearing Headset is designed to work with all “Campy” style integrated headtube frames. It uses an Sealed 45/45 ACB (Angular Contact Bearing) for the greatest amount of bearing contact and the smoothest spin. The top race is machined from light weight aluminum and has rubber dust seals to help maintain the life of the bearings. These headsets are for use in 1 1/8″ / 1.5″ tapered head tubes only.