Non standard bearings, also known as non-standard bearings, refer to bearings that do not meet the external dimensions specified in national standards, that is, all bearings with external dimensions different from those specified in national standards. Its main characteristics are low universality, mostly for special equipment and special occasion applications, small batch size, and the majority of newly developed equipment trial products; However, due to its non large-scale and mass production, there are not many production enterprises, and the cost is high and the price is expensive.