This product is either discontinued or we cannot get that from suppliers.
Qnap RAM-4GDR4K1-SO-24 RAM Module, Memory Size 4 GB, DDR4 RAM, Speed 2400 MHz, Number of Pins-260, Form Factor SO-DIMM.
The QNAP RAM-4GDR4K1-SO-2400 is a DDR4 SO-DIMM RAM Memory which is used for upgrading NAS storage. The QNAP RAM-4GDR4K1-SO-2400 memory provides 4GB Memory with DDR4 SO-DIMM RAM 2400 MHz.