I just received them, good quality in terms of construction, but be careful to wash them well and leave them outside the house for a few days. I slept in the room and woke up the next day with a terrible throat and a stuffy nose because of the smell, that's why the rating.

It is simply a bulky disk, but it is logical considering that the weight missing from the material that would fill the gaps, since it is a steering wheel disk, must be replenished in some way.