To create the best possible shifting performance with their new Dyna-Sys 10-speed components, the Shimano CN-HG94 HG-X 10-Speed Chain is directional. By that, we mean to say that it can only be installed one way. The reason for the specific installation is that it has four different plates -- both sides/inner and outer.
Since the action of climbing up the ramps and pins from one chainring to another is slightly different from climbing up one cog to the next, Shimano chose to shape the left and right side plates differently to optimize the chain for each specific purpose. The result is a chain that works in harmony with their new 10-speed system to provide a shift quality unrivaled by any of their previous efforts. The Shimano CN-HG94 10-Speed Chain has zinc alloy plated links to give it a nice corrosion resistant finish.