a few yrs back i had a set of yellow tuffs, that i think i got fom rhys, lazychubs, with alloy colour hubs, with open bearings, not sealed, that were stamped graphite.
i put this down to the fact that they may have been a later run of alloy hubbed style, just before the plastic hub introduction, and skyway just wanted rid of their hubs that they had laying around, so anything got used, dont know though!!
Dave