If you happen to have 6600 or 7800 cassettes, they will work just fine on a 6700/9000 drivetrain. Or on an Sram 10sp drivetrain. I've been using the on my Sram bike. They work better than Force cassettes. Some people have been able straighten large staples and use them as shims between the cogs and freehub. Mostly on Tune hubs.