The centerlock tool is a guide tool that screws into your hub and allows you to slide your wheels on and off without hitting your rotors, this is most important on PCCB rotors but it sure makes it easy on your back even with steel rotors. See this thread. The forum cut off the last 33 pages of it.
https://rennlist.com/forums/997-gt2-...ment-tool.html
Cheers
Ed