Size: 1.5" Crown races, compression rings and bearings for servicing Cane Creek headsets (see headset for other parts) * Upper and lower replacement bearings sold as a set for tapered fork headset applications ** AER series bearings are cross-compatible across the line, using aluminum and steel construction, 35% lighter than 110 and 40 series bearings 40-series crown races are cross compatible with all series headsets