The Giant frames with internal headsets comes with the headset. If you want a new one to fit such a Giant you can get one from Cane Creek (any of the ZS models) or FSA (one of the Orbit models). Good headset companies include Cane Creek, Chris King, FSA, Hope, Race Face, Ritchey, and Syncros. It really is hard to mess up a headset . Chris King does make an internal headset, but it often requires modification of the frame to fit, so it's generally not an option.