v-Color 32GB (2 x 16GB) ECC SO-DIMM DDR4 2666MHz (PC4-21300) for NAS Micro Server/Workstation/Compatible with Synology 21 Series 2Rx8 CL19 1.2V (TES416G26D819K-VKC) at Amazon.com
Amazon.com: Crucial 8GB Single DDR4 2666 MT/s (PC4-21300) SR x8 DIMM 288-Pin Memory - CT8G4DFS8266 : Everything Else