Shimano Cn-HG901 Dura-Ace/XTR HG-X 11-speed ChainSuper narrow lightweight 11 speed HG EV symmetrical design chain for smooth shifts and maximum durability Outer plate design has been developed to reduce the chance of chain suck Sil Tec surface treatment technology (PTFE plating) on inner and outer links and rollers that is smooth running and increases durability Zinc Alloy plated inner and outer links Hollow pin for added weight saving The inner plate has been developed for better contact with gears