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: CORSAIR VENGEANCE RGB PRO 16GB (2x8GB) DDR4 2666MHz C16 LED Desktop Memory - Black : Electronics
Corsair CMK64GX4M4A2666C16 Vengeance LPX 64GB (4x16GB) DDR4 2666 C16 Desktop Memory Kit for DDR4 Systems at Amazon.com
Micron 16GB DDR4 SDRAM Memory Module at Amazon.com