FC connectors are mainly used in the USA and Asia. There they are mainly used in telecommunications.
In order to limit the contact force of the end face and enable physical contact between two end faces, FC connectors have an axially spring-loaded pin. They feature torsion protection and are locked with a thread. Their ferrule has a diameter of 2.5 mm.
FC connectors are primarily used for single-mode applications. Multi-mode versions are also available.