For 2015, Shimano's 105 groupset got a few high profile upgrades. It's gone to 11 speed, and now has many of the same crankset technologies seen in Dura Ace and Ultegra. As you'd expect, changes to the cassette and crankset also necessitate changes to the chain that connects them. Shimano designed the new CN HG600 11 speed chain as one of the new 11 speed chains from the Japanese manufacturer. The HG600 differs from the HG900 in that it uses solid pins instead of hollow. This amounts to a weight gain of about 0. 08 grams per link, but it also adds to the durable reliability of the only chain worthy of being associated with the hardworking 105 group. Despite its slightly higher weight, it does receive the same revolutionary new Sil Tec ultra low friction treatment as its more expensive sibling. Sil Tec reduces friction dramatically while also increasing the chain's longevity and decreasing noise. Please note that while it's specifically designed for the new 11 speed 105 5800 groupset, the CN HG600 is also compatible with 11 speed mountain drivetrains.