It is an additional wire for above phones to connect with UFS, Twister Flasher, Tornado Box (UFS2, UFS3 and all other boxes with compatible RJ45 socket.
This cable fits the following models: Samsung SGH-705SC, 706SC, 707SC, 707SCII, 709SC, SGH-A411, A412, A436, A437, A701, A706, A707, A707C, A711, A717, A727, C170, C520, D520, D800, D807, D820, D830, D840, D900, D900i, E200, E230L, E236, E250, E250D, E250i, E250V, E390, E420, E480, E490, E500, E570, E590, E690, E740, E780, E790, E830, E840, E870, E890, E900, E950, F300, I600, I607, J600, J600E, M300, P300, P310, P900, P910, P920, S501i, S720i, S730i, T219, T219s, T329, T509, T519, T629, T649, T809, U100, U300, U600, U600B, U600G, U700, U700B, X576, X820, X830, X830N, X836, Z150, Z170, Z230, Z240, Z240E, Z330, Z350, Z360, Z370, Z400, Z510, Z520, Z540, Z550, Z560, Z600, Z620, Z630, Z650i, Z710, Z720, Z720M, ZV40, ZV60