Designed for their TS-x83XU series, the 4GB DDR4 2666 MHz UDIMM ECC Memory Module from QNAP is a single RAM module that will let you upgrade the overall memory capacity of your compatible NAS. It features a capacity of 4GB, a clock speed of 2666 MHz (PC4-21300), and a 288-pin DIMM form factor. It operates using 1.2V, supports ECC technology, and is not buffered/registered.