More info. The front rotors measure 320 MM Dia / 30MM Tk and have curved vanes but are not cross drilled. These look to be regular SL 500 rotors. The SL600 is supposed to be 334MM Dia / 32 MM TK , curved vanes and are cross drilled. The SL320 had 300 Dia / 27.9 Tk with straight vanes.