With the introduction of the 12-speed drive into the Deore XT group, a new type of freewheel had to be introduced to assemble cassettes with very small sprockets.
For example, the Micro Spline freehub was developed in cooperation with DT Swiss. This allows Shimano to use cassettes with enormous bandwidths and the use of a small 10 tooth pinion. At the same time, the freewheeling principle was changed from pawls to a pulley freewheel. Due to the very fine toothing shrinks the distance of the locking points to a low 7 °. The free travel when pedaling is immensely reduced and allows you always the best possible start, whether in the race or on the trail.
What's left is the durable and robust bearing the hub - tried and tested cone bearing with hardened and polished steel bearing shells and stainless steel balls. In conjunction with labyrinth and contact seals a long life and the known silky smooth running of the hub is achieved.