Non-standard bearings: Non-standard bearings are non-standard bearings. Generally speaking, they are bearings that do not meet the external dimensions specified by national standards, that is, all bearings whose external dimensions are different from national standards. Its main features are low generality, mostly for special equipment and special occasions, small batches, and trial products of new research and development equipment account for the majority; but due to its non-scale and batch production, there are not many production enterprises and high costs , The price is more expensive. Standard bearings: The inner or outer diameter, width (height), and dimensions of standard bearings conform to GB / T273.1-2003, GB / T273.2-1998, GB / T273.3-1999 or other relevant standards. Model size. Non-standard bearings are non-standard bearings that do not match the size and structure of standard bearings, that is, bearings produced according to customer requirements. Non-standard inside and outside 49, standard 50, everything else is the same. The 49 is a non-standard, you need to follow the size and structure ratio in the customer’s book, otherwise you don’t know if the 49 is a national standard or a non-standard. Other structures are different. For example, there are many steel ball rollers. Or less. This rare, generally can be universal full name is non-standard bearings.