Royce Titanium Lockring For 9-Speed Campagnolo Hubs - 26mm Thread From  £42.50

They do their job.

Earlier 9-speed exa-Drive freehubs lock ring threads were 26 mm while later 9-speed freehubs were 27 mm (which carried over to 10-speed free hubs). 10-speed cassettes easily mount to 26 mm threaded freehubs EXCEPT there are no Campagnolo produced 27 mm thread lock rings for 11 tooth small cogs. By offering this lock ring Total Cycling solves this problem for cyclists like me who mix and match newer and older Campagnolo hardware.