How do I know which one is genuine on SM-RT66 rotors? One says made in China (SK) while other says Japan (RA). Both has different edges. Please confirm. Got china one from
Disque de frein vélo Ø160 mm 6 trous Shimano SM-RT66 – Pièce vélo VTT
Shimano SLX SM-RT66 Disque de frein vélo VTT VAE
Shimano cc402761 disque de frein a disque sm rt66 180 mm 6 trous Disq