A-Tech 4GB Module for QNAP ES1640dc Series NAS Servers - DDR4 2400MHz PC4-19200 Non-ECC DIMM 1.2V Memory RAM (Replacement for QNAP RAM-4GDR4A0-UD- 2400) at Amazon.com
Arch Memory Replacement for Qnap RAM-4GDR4A0-UD-2400 4GB 288-Pin DDR4 2400 MHz UDIMM RAM for TS-1635AX at Amazon.com