SMA is a fiber optic connector developed and manufactured by Amphenol Fiber Optic Products; it stands for SubMiniature version A.

SMA connectors use a threaded plug and socket. It was the first connector for optical fibers to be standardized. The SMA was designated as FOCIS-1 by the TIA.

In addition to their compact size, the SMA connector has exceptional mechanical durability. The SMA connector holds a single fiber. SMA connectors have a threaded coupling nut. The ferrule is traditionally made of steel, although ceramic versions are available.

SMA connectors come in two varieties: the SMA-905 has a straight ferrule, whereas the SMA-906 has a stepped ferrule design. The SMA-905 is a non-contact connector typically used in medical, industrial, and military applications. When two SMA 906 are mated together the stepped ferrule design allows an alignment sleeve to be used and therefore the connection has lower insertion loss. The SMA 905 does not have an alignment sleeve therefore the insertion loss of the 905 is higher than that of the 906.