Qnap RAM-4GDR4A0-UD-2400, 4GB DDR4, 2400 MHZ, Signal Processing Unbuffered, Number of Pins 288-pin, Form Factor DIMM. This 4 GB DDR4 RAM Module is compatible with TS-x73U and TS-x73U-RP Rackmount NAS CPU Series. This 288-Pin unbuffered DIMM module is designed to run at 2400 MHz frequency.