Yet another winner from Shimano. The Dura-Ace CN-7901 chain features the world's first asymmetric design. The outer plates are shaped to reduce the chance of the chain dropping between the chainrings and the inner plates are made to interface with the cassette cogs in a precise manner reducing drivetrain friction and helping to deliver more watts to the rear wheel. Other benefits are smoother shifting under load, quieter performance, and improved durability. Cutout side plates and hollow pins bring the weight of the chain down to 252 grams saving about 18 grams from the 7801 chain. In a nutshell, it is smoother, lighter and more expensive than it's predecessor. Works on all 10 speed Shimano drivetrains, in fact you may find it improves shifting performance on other manufacturers drivetrains too.
Initially when this chain was introduced, Shimano included a quick-release master link. It actually installed quite easily, but wore quickly and tended to cause a variety of issues. Needless to say these links have gone the way of Bio-Pace, Positron, Santé, Dual Control and other attempts of engineering success. The 7901 chains are now issued with the good ol' tried and true HG chainpin. It works perfectly, just like always and is totally reliable.