The HG50 is the least expensive Hyperglide compatible cassette Shimano makes.
The lockring is made of steel with a black finish, and the first through the sixth position cogs are made of steel with a brown finish. The seventh position cog is plated in a Silver color that is likely Nickel or Zinc.
The HG50 cassette is the stock cassette sold with all of Shimano's less expensive parts groups. It is compatible with, and can be used on 8 speed XT, DX, and LX mountain hubs also the older 8 speed Dura-Ace, Ultegra, 105SC, and RX100 hubs. It is compatible with XTR or Dura-Ace, Ultegra, or 105SC 8 speed hubsets.
Understand that the HG50 is functionally the equivalent of the HG70, and HG90, it's just not fully plated like the 70 & 90, (to prevent rust), and the unit is riveted together.
