KMC Z8.1 Chain - 7 or 8 speed Grey
100% Compatibility On All 7 or 8 Speed Derailleur Systems
Added Chamfering for Smooth Operation
Impeccable Precision Phenomenal Shifting Performance
There isn't much difference between the X8 and the Z8 series, other than the Z8.1 is a bit more reinforced, and therefore a bit heavier. The X8 is a bit lighter and is advertised as being more precise and shifting better. The main reason we have both of these is just availability and supply though. Don't sweat it, they're both great chains.