I'm showing on the Sachs site, that it's 8.5" OD, 13/16" ID, and 24 Teeth.

P/N KF117-02

What is the original material? Some kind of metalic or ?

You might want to take it to a brake / clutch specialist, and have them put new "pucks" on it. That's what I've done with my VW clutch disk.