Manufacturer's Description
Nickel plated inside and out, our PC-991 Power Chain II looks good
enough to wear. But that would be a serious waste of performance. The
nickel plating is there for faster, more accurate shifting in all
conditions, not blingage. Exclusive PowerLink™, technology closes the
chain (and the loop).The Hollow Pin PC 991 chain features a special
hollow rivet pin to reduce weight yet still retain its powerful push-pin
strength.