Optical Fiber Adapter is used to mate two connectors, usually mounted in a distribution panel or wall mount box. It is a precision components made from zirconia ceramic to ensure the perfect alignment of connectors and reduced insertion loss for both SM and MM fibers. In most cases, the split sleeve is the critical part of the system that aligns the ferrule part of the connector, keeping the fibers in perfect alignment.

In the case of MT-RJ, the alignment is carried out by two guide pins fitted into one of the connectors. The adapter is purely to support and lock the connectors together in the distribution panel or wall box.