Shimano Dura-Ace Rotors RT-MT-900SS v RT-MT-900S

[matt456]

Hi, Just wondering what the difference is between Shimano Dura Ace Rotors, one ends in SS and the other with just S.
My front wheel has RT-MT-900S stamped on the rotor.
Rear wheel has RT-MT-900SS stamped on.

I can't seem to find any information on the internet that explains it. Also when going to buy replacement most websites just list them as RT-MT900 rotors with no mention of any S.

If anyone knew the difference, I'd be glad to know it.
Thanks.

[Duck!]

The difference is rotor diameter. SS (Super Small) is 140mm diameter. S (Small) is 160mm. There is no other difference between them.