Originally Posted by
FBinNY
I don't know if they've changed since, but low and middle level Sram cassettes didn't include lock rings. The better ones did.
Foe quite a while, all Campy cassettes with a 12T or larger smallest cog didn't come with a lockring and the lockring came with the hubs. Only 11T cassettes included the lockring. Now all Campy cassettes include the lockring.