The TE Connectivity 5503137-6 is a duplex fiber optic adapter that converts between an SC receptacle on one side and an ST receptacle on the other. It accepts both Singlemode and Multimode connectors — the ceramic ferrule bores are sized for the 2.5 mm ferrule common to both SC and ST, so the same adapter body works with either fiber type. The beige housing is the standard colour for multimode components, but the adapter itself is rated for both modes, meaning you can patch a singlemode SC patch cord into a multimode ST bulkhead or vice versa — the adapter does not enforce mode purity; that is a system-level decision. The duplex format carries two independent fiber channels in one housing — one for transmit, one for receive — matching the typical bidirectional pair in a transceiver link. The adapter mounts into a panel cutout via the integral flange and snap-in clips; no separate mounting hardware is needed beyond the panel hole. A dust cap is included on each port to keep the ferrule alignment sleeves clean when the adapter is not mated.
The ferrule alignment sleeve is ceramic — the standard material for precision fiber alignment in SC and ST adapters, giving consistent insertion loss across repeated mating cycles. The housing is glass-filled PBT, which holds its dimensions through the temperature and humidity swings of a telecom cabinet or industrial control panel.
The 5503137-5 is the simplex (single-channel) version of this same SC-to-ST adapter body. The 5503137-6 is the duplex version — two fiber channels side by side in one housing. Everything else — the ceramic ferrule, the beige PBT housing, the panel-mount flange, the dust caps — is identical between the two. The choice comes down to whether your link needs one fiber (simplex) or a transmit/receive pair (duplex).