This part is intended to be used to minimize geometry changes when running a 26" fork in a 27,5" frame. But you can also use this part to change the effective head angle of any bike with ZS56 head tube. On the inside the cup is machined to fit with IS52 standard. This means you can combine this cup with any IS52 haed set.
The cup will give you an additional 12 mm of stack height. Using a Cane Creek IS52 this will result in a total stack height for the bottom of 16 mm. The outside diameter is chosen to give a perfect match with the COAL head tube.