Sugino Gigas Track 12t Cog Lockring (NJS)

This Sugino lockring is designed specifically for use in conjunction with the Sugino Gigas 12T track cog.
It will also be beneficial for use with other 12T cogs, too, in cases where the chain might rub against the locking.
This lockring gives the chain more clearance, so your chain does not touch the lockring.
If you are running a 13 tooth or larger cog, it makes sense to go for the cheaper Shimano Dura Ace NJS lockring, which can also be found at Track Supermarket, although this can be used with all cog sizes, not just 12T cogs.