Original Cannondale headset for 2018 generation Synapse carbon frames.This headset fits frame sizes 44cm and 48cm.Use kit K35018 for 44 and 48cm frames. Use kit K35028 for 51 and 54cm frames. Use kit K35038 for 56, 58, and 61cm frames.Headset includes:Carbon conical spacerFlat alloy top plateUpper bearing wedge1 1/8" upper bearing1 1/8" lower bearingCrown race not included as it is integrated into the fork