This product is either discontinued or we cannot get that from suppliers.
QNAP 8gb Ddr3 Ram Expansion For RAM-8GDR4K0-SO-2133, 8GB, DDR4 SDRAM, Speed 2133 MHz, 260-pin, FF SoDIMM.
The 8GB DDR4 2133 MHz SO-DIMM Memory Module from QNAP improves the performance and application responsiveness of your NAS storage.