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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
HyperX FURY HX426C16FB4K2/32 32GB (2 x 16GB) 2666MHz DDR4 DIMM Desktop Memory Kit Black HX426C16FB4K2/32 - Best Buy
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
Amazon.com: OWC 32GB (2 x 16GB) PC19200 DDR4 2400MHz SO-DIMMs Memory Compatible with Mac Mini (Late 2018), 27" and 21.5" iMac (Mid 2017), and Compatible PCs (OWC2400DDR4S32P) : Everything Else