D4EC-2666-16G16GB DDR4 ECC Unbuffered DIMM EAN: 4711174723751 Applied Models*: SA series:SA3200D UC series:UC3200 21 series:RS4021xs+, RS3621xs+, RS3621RPxs, RS2821RP+, RS2421RP+, RS2421+ 19 series:RS1619xs+ 18 series:RS3618xs, RS2818RP+, RS2418RP+, RS2418+ 17 series:RS4017xs+, RS3617xs+, RS3617RPxs * To install this memory module on RS4017xs+, please make sure your Synology NAS runs on DSM 6.2.2-24922-6 or above.