What is the Fibroptico FO-GLC-5531DD-10?
The Fibroptico FO-GLC-5531DD-10 is a SFP optical transceiver module, listed by the manufacturer as "GLC-5531DD-10 1000BASE-BX-D BIDI SFP 10KM TX1550NM/RX1310NM SIMPLEX LC CONNECTOR COMPATIBLE CISCO". It is part of Circular Telecom's surplus and refurbished telecom/IT equipment inventory.