The Ultegra 6800 11 Speed chain is narrower and lighter than its 10 speed predecessor. The new 6800 chain is coated with Sil-Tec treatments which make for lower friction, better life, and a quieter performance. The inner width of the chains has stayed the same, meaning the Ultegra 6800 cogs and chain rings are still the same width. Completely compatible with Dura Ace 9000, giving you the option to mix and match between the two groups. The only limitation (if you want to call it that) with the Ultegra 6800 11 speed chain, is it is not backwards compatible with 10 speed components.