Shimano Hyperglide-C (C stands for "Compact") cassette lockring
Color/finish: BLACK OXIDE (NOTE THE PICTURE - these come in bags of 10 from Shimano and the
lockrings are just all thrown in the bag without individual packaging - hence the scratches.
This is what you will receive. This is what bike shops received back in the 1990's.
"Show quality" doesn't exist and never did for these. Please keep this in mind if you purchase.)
If you don't understand about the Hyperglide compact cassettes, read this before purchasing: http://sheldonbrown.com/k7.html#hyperdrivec
You can use these on existing compact cassettes or if you are converting a cassette with a larger than 11T top gear to 11T.
Oddly, Shimano doesn't put the part number on this part - but doing a bit of looking around the web,
it appears this is part number 11E01400 and is for the CS-HG50 7-speed cassettes.
These were purchased in bulk so there is no retail packaging.