What is the Gigatech J4859D-GT?
The Gigatech J4859D-GT is a SFP optical transceiver module, listed by the manufacturer as "HP Compatible 1G SFP, 1000BASE-LX, 1310 nm, 10km SMF LC, DDM, CTemp". It is part of Circular Telecom's surplus and refurbished telecom/IT equipment inventory.