The function of a fiber optic adapter is to provide housing for connectors. Thus a fiber optic adapter connects two connectors in a fiber optic line. Adapter is a mechanical fixture designed to interlock fiber-optic connectors. The adapter contains a split sleeve, also known as the interconnect sleeve, that holds the mated connector ferrule end-faces together and in proper alignment. The material of the adapter can be metallic or plastic. Selection of material depends on the specification such as alignment accuracy. Adapter sleeve can be made of polymer, phosphor bronze, stainless steel or ceramic materials.
On the other hand a bare fiber adapter is used to link the bare optical fiber to fiber optic equipment temporarily. In the market, bare fiber adapters are available for purchase with FC, SC, ST. LC, MU, SMA connectors with round or square type press button.