Listen to me. In the absence of equipment, distinguishing bearings is divided into three steps: seeing, touching and knocking. Mainly depends on the packaging of the bearing, whether the packaging is neat or not, and then on the gloss of the bearing. A good bearing external light will look a little black, and the external light is the kind of black and bright. On the contrary, what looks rough belongs to inferior products. Then see if the chamfer of the bearing is bruised or touched. If so, it is produced by a small factory. Second, look at the bearing clearance and friction coefficient. Pick up the bearing with both hands, press the inner ring up and down with your thumb and forefinger, and swing it up and down gently, and you will feel the clearance of the bearing. Look at the friction coefficient of the bearing. For some small bearings, pick up the index finger with one hand and put it on the inner ring, press the thumb on the outer ring and turn it back and forth hard. For poor quality bearings, your index finger will feel sand, just like there is sand in the bearing groove. The lighter the feeling, the more accurate the treatment. In this case, it is to judge the material and hardness of the bearing. If two bearings collide hard, if there are traces of white marks on the surface, or there are no traces, it means that the material is better. In severe cases, dents appear, indicating that the bearing hardness is not enough, and the material is iron or carbon steel. I don't know if you understand. I'm exhausted. I typed so many words.