If you need to convert a Lefty or Headshok frame to use a standard 1.5"-1/8" tapered fork, this is the headset you need.
This is for Si frames that take the Headshok headset bearing straight into the frame without the use of cups. Frames that are like this include the Rize/RZ, Scalpel 29, F-Si series and some carbon bikes. If you have "System Integration" written on black cups pressed into the frame, this will work, but it presses into those cups increasing the stack height.
Kit includes bearings, crown race, adapters, top bearing wedge, top plate, and optional stack height spacer for the bottom for increased crown clearance with certain forks.