The fork is the part of the stunt scooter to which the front roller is attached. She goes through the headtube on deck to the bar.
The forks are built for different compression systems:
SCS - The Standard Compression System has two different parts. One part is for the fork - mostly with a 28mm diameter, the other part is for the bar (which with the SCS system must not have a slot at the bottom). Here you can choose different sizes to be able to monitor different bars, regular 32mm or oversized 35mm.
HIC - Hidden Internal Compression - is used with bars (about 32mm diameter). The shim is available in plastic or metal and in different lengths and shapes.