If your bike has a Scott Syncros 1.5 headset system, you will need this adaptor in order to fit your Shotgun Pro.
Fitting the Shotgun Pro on a Scott bike with Syncros stem system requires a minimum of 15mm stem clearance (from headset to the bottom of the stem).
The Shotgun Pro spacer (provided with your Pro seat) will replace two of your existing 5mm spacers, and the Scott Syncros adapter will replace one of your existing 5mm spacers.