FSA replacement headset bearing for first generation Synapse Carbon frames from 2006-2008. Owners manuals state the correct kit as KB002/ but the correct bearings are taller and have a different angle bearing. Match your bearings against the photos to match what you need.
This headset bearing may work with other frames and headsets - it only fits a small number of Cannondale frames w/ 45/45 degree bearings.
Bearing measurements: 41.8mm outer diameter, ~30mm inner diameter, 8mm overall height.