The Cannondale Kit Headset Internal 1.5 HeadShok replaces the standard Cannondale bearings to enable you to run a 1.5 fork and stem.   This fits directly into Cannondale frames that accept the HD169 bearings without the need for the SI cups. Rush Carbon, Flash Cannondale Kit Headset Internal 1.5 HeadShok Features Adapter kits for converting Headshok frames to run either 1.5, tapered or 1 1/8 steerer forks include: cartridge bearings, crown race and upper bearing top cover Outer needle bearing races come in 3 lengths, and 4 thicknesses Inner needle bearing races come in 7 lengths, and 7 thickness: call Cannondale direct to confirm compatibility