What is non-standard bearing?

Non-standard bearings, is not in line with the national standards for the size of the bearings, also known as the overall size of the national standard is different from the provisions of all bearings.
Its main features are low degree of versatility, many for special equipment, special occasions, small batch, new research and development equipment trial products accounted for the majority, but because of its not large-scale, batch production, production enterprises are not many, the cost is high, the price is more expensive.