QNAP 4GB DDR4 RAM, 2666 MHz, SO-DIMM, 260 pin, T1 version Applied Models: TS-435XeU, TS-453DU(-RP), TS-473, TS-673, TS-873, TS-832PX, TS-853DU-RP, TVS-472XT, TVS-672XT, TVS-872XT, TVS-473e, TVS-673e, TVS-873e, TVS-672X, TVS-872X, TVS-672N, TVS-872N, TS-473A, TS-673A, TS-873A