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
Kingston 16GB DDR4 2666MHZ SODIMM at Amazon.com
16GB Memory for MSI GP63 Leopard 8RE-077US DDR4 2666MHz SODIMM RAM (PARTS-QUICK Brand) at Amazon.com