Came with the NAS before being removed and upgraded, fully working. D4EC-2666-8G DDR4 Compatible Models SA series: SA3400D, SA3200D UC series: UC3400, UC3200 21 series: RS3621xs+, RS3621RPxs, RS2821RP+, RS2421RP+, RS2421+ 19 series: RS1619xs+ 18 series: RS3618xs 17 series: RS4017xs+, RS3617xs+, RS3617RPxs
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