ST to ST (Female to Female) Simplex Fiber Optic Adapter/Coupler. ST adapters uses ceramic sleeve to connect between two ST fiber Optic cables. Adapters can lock the connectors and get low insertion loss to transmission optical signal. Our ST fiber optic adapter are suitable for fiber patch panel, which means you can use them in any type of enclosure with rectangular cutouts. Meets the Telcordia and IEC 61754 stander, all materials compliant with RoHS requirement.