He states the number 6 is for boxxers and a 205 rotor, I'm 99% sure he means 200mm rotor as back when non mono m4s were around rotor sizes all seemed to be 160, 180, 200 etc. I think 165, 185s etc didn't come in until later.
Sorry I can't be clearer but been so long since I ran the brakes this disc was intended but never usedfor.