The HG70 7/8 speed cassette is the next step in the Shimano line and comes stock with the Deore LX, and came with the discontinued DX parts group. In road racing it is supplied with the RX100 and the 105SC parts groups.
They will, however, work on all Shimano 7 or 8 speed HyperGlide hubs, including Dura-Ace, and XTR (if you elect to use them), STX, Deore XT, Ultegra, 105SC and the less expensive parts groups. The HG70 uses cold forged cogs. All of the cogs, and the lock ring are plated in a dull Silver colored finish to prevent them from rusting, (probably Zinc, or Nickel, it's difficult to tell).
The second position cog has three threaded holes for the cassette binder bolts to thread into from the rear of the cassette unit. The cogs are 1.9mm thick and are spaced apart with 3mm plastic spacers. The binder bolts are un-plated Black steel with a 4mm six sided head.
The HG70 8 speed cassettes are for use with Dura-Ace, Ultegra or 105SC 8 speed hubsets.
