This is Marwe's skate rear wheel without the ratchet functionality of the front wheel. You get a choice of 3 hardness' that you can then utilise to get more out of your workout by for instance going with the slow version. This wheel is mounted on the rear end of roller skis.
The rubber used is Marwe's popular blend that yields durability and good wet grip capabilities.
The wheel comes complete with bearings and an axle pre-installed.