A slightly thicker mantle layer and firmer cover than the Tour i. This helps give added distance on the long shots and control on high-spinning pitch shots. The cover design negates the need for a seam.
This definitely feels firmer than the Tour i, but still feels softer off the putter face than many others. The firmer cover did not cut up on pitch shots as much as its softer counterpart, but there is still plenty of control on offer.