Newest 12 speed cassette from Shimano in the 105 series, which is the series under the Dura Ace and Ultegra series.

The cassette is made for Shimano's new Spline system that creates a larger contact surface between the cassette and the cassette casing for better power transfer. They have therefore been developed for the new Spline, but can also be used on 11 speed HG cassette cases.

Unlike the 11 speed cassettes from Shimano, you get a more even exchange on the gears and especially the gears that Shimano calls the "sweetspot gears" have less jump between each other. In addition, the profile of the teeth is different than before, which ensures more consistent gear changes even under high loads.