My experiences with Chinese precision items is that they aren't. Precision that is. Truly junk. I've been told there are differing levels of Chinese products but I've not found any of the good stuff. I avoid them at all costs.
I work for a semiconductor manufacturer that has a plant in China. If "they" can make structures that are mere atoms in thickness then I think they can make ball bearings. It all comes down to quality control (which is an added expense to the overall part cost).