This product is either discontinued or we cannot get that from suppliers.
QNAP 4GB DDR3 1600MHz SO-DIMM, Component for Notebook, Internal memory 4 GB, Memory layout (modules x format) 1 x 4 GB, Internal memory type DDR3, Clock speed memory 1600 MHz.
QNAP RAM-4GDR3T0-SO-1600, 4GB DDR3 RAM, 1600 MHz, SO-DIMM.