Synology RAM DDR4-2666 Non-ECC SO-DIMM 4GB (D4NESO-2666-4G) at Amazon.com
PNY Performance 16GB DDR4 DRAM 2666MHz (PC4-21300) CL19 (Compatible with 2400MHz or 2133MHz) 1.2V Notebook/Laptop (SODIMM) Computer Memory RAM – MN16GSD42666 at Amazon.com
Amazon.com: OWC 32GB PC19200 DDR4 2400MHz SO-DIMM Memory Compatible with 21.5" and 27" iMac Retina Models (Mid 2017), Mac Mini (Late 2018), and Compatible PCs (OWC2400DDR4S32G) : Everything Else
OWC 8GB (2 x 4GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S08P)
G.Skill RipJaws SO-DIMM Series 32GB (2 x 16GB) 260-Pin (PC4-19200) DDR4 2400 CL16-16-16-39 1.20V SO-DIMM Memory Model F4-2400C16D-32GRS at Amazon .com
Silicon Power Hynix IC Compatible for Apple DDR3 DDR3L 16GB (2 x 8GB) RAM 1600MHz (PC3 12800) 204 pin CL11 1.35V Non ECC Unbuffered SODIMM Laptop Notebook Memory RAM Module Upgrade
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